Calculator Methodology & Editorial Standards

Who builds these calculators

CalcSystems is currently a small project, not a multi-author publication. The calculators are built and maintained by a single editor who is not a CFP, CPA, attorney, or licensed financial professional. We do not employ external reviewers. When a tax bracket, contribution limit, or formula needs verification, we cite the primary source (IRS, SSA, FDIC, CFPB, etc.) directly on the calculator page rather than rely on a generic "reviewed by [expert]" badge.

We mention this up front because it's increasingly common for small finance sites to imply professional review where none exists. We'd rather be honest about scope: these are well-maintained reference calculators, useful for sanity checks and back-of-envelope work. They are not a substitute for a qualified professional reviewing your specific situation. More on who builds this and why is on the about page.

What we publish on every calculator

Every finance, tax, payroll, loan, mortgage, CD, savings, and inflation calculator on this site shows a standardized Methodology & Sources block near the results. It includes:

Last reviewed — the month/year we last verified the formula and data.
Tax/data year — which year's brackets, limits, or rates the calculator uses.
Formulas used — the actual math, written out in plain language. No "trust us."
Assumptions and limitations — what the calculator simplifies, ignores, or approximates.
Primary sources — direct links to IRS publications, SSA tables, FDIC regulations, state revenue departments, etc.

How we handle tax-year data

Tax-sensitive calculators (income tax, paycheck, capital gains, self-employment, 401(k), RMD, sales tax) are versioned to a specific tax year. When the IRS releases new brackets, we:

Update the underlying data files in src/data/ with the new figures.
Bump the calculator's Last reviewed date and tax-year fields.
Add a one-line entry to the calculator's "what changed this year" summary where it materially affects results.
Re-verify worked examples against the IRS / SSA / FTB published examples where available.

Brackets that are inflation-indexed (the federal income tax bands, Social Security wage base, 401(k) contribution limits, FSA caps) are pulled directly from primary sources, not third-party aggregators.

Source policy

We prefer primary sources. In rough order of trust:

Statutory and regulatory texts — IRS Title 26, Social Security Act, state revenue codes.
Government agency publications — IRS Pub. 15 / 17 / 525, SSA fact sheets, FDIC Truth in Savings, CFPB rulemaking pages.
State and city revenue department guidance — official withholding tables and bracket schedules.
Federal Reserve and BLS data — for inflation, CPI, and rate-history calculators.

A few figures have no government source, and for those we name the organization that publishes them: market rate surveys (Freddie Mac for mortgage rates, Bankrate for auto loan and CD rates), the Tax Foundation's population-weighted average local sales tax rates, and the National Association of Realtors' buyer survey. Calculator aggregators and blog posts are not cited as authority. If we can't trace a number to a published source, we don't publish it.

What our calculators don't do

They don't give financial, tax, or legal advice. They run formulas on the numbers you enter. Edge cases — multi-state work, alternative minimum tax interactions, phase-outs, equity comp, partnership distributions, foreign income — usually need a professional.
They don't model every fee. A CD calculator computes the maturity value implied by the APY; it does not model maintenance fees, leap-year crediting conventions, or partial-year holiday effects. We disclose this on each calculator.
They don't account for personalized scenarios. Filing status interactions, deduction phase-outs, dependent rules, and credit eligibility have edge cases that a generic calculator can't capture without becoming the IRS.

Errors and corrections

We make mistakes. If you spot one — a wrong bracket, a stale tax year, a formula bug, a typo — please let us know and we'll fix it. Every correction is logged here, in one place, with what was wrong and what it is now. Each calculator's Methodology & Sources panel links to this log; the panel's "what changed this year" note covers new laws and new official figures, not our own fixes.

We publish this log rather than quietly overwriting numbers. If a figure you relied on has changed, you should be able to see that it changed and why.

November 2026

November 3, 2026 — CD Calculator (stated fact). The 3-year CD section said the best 3-year rate was above the best 5-year. That was true of the October 8 rates but not after the October 21 refresh, when the page showed 4.85% for 3 years and 5.00% for 5 years beside that sentence. The comparison is now generated from the rates shown. Calculator results were not affected.
November 3, 2026 — 2027 tax figures page (stated fact). The page said every tax calculator ran on 2026 figures and none used the 2027 projections. Since September 11, 2026, the income tax and paycheck calculators have offered 2027 as a projected year. The page now says so.

October 2026

October 30, 2026 — Salary to Hourly Calculator (formula description). The methodology panel said weekly pay is the annual salary ÷ 52 and biweekly pay is the annual salary ÷ 26. The calculator actually divides by the weeks you enter (weekly = hourly rate × hours per week), so the description was wrong whenever weeks per year was below 52. The description now matches the calculation; results were not affected.
October 16, 2026 — Pennsylvania Paycheck Calculator (stated fact). The page said the Local Services Tax is capped at $52 a year. That is the general cap, but financially distressed cities can charge more: Harrisburg and Scranton charge $156, with exemptions for people earning under $24,500 and $15,600. Corrected when the calculator began computing local taxes from the state's Act 32 register. Take-home figures were not affected, because the calculator did not include the Local Services Tax before.

September 2026 review

From September 23 to 25, 2026, every calculator, state page and guide on the site was checked again against its primary sources: IRS and state revenue publications, SSA, BLS, BEA and the other sources named on each page. The 57 corrections from that review are listed below, newest first. Each one is fixed on the live site.

Show all 57 corrections from the September 2026 review

September 2026 — Analytics (privacy). Our privacy policy says the numbers you enter never leave your browser, but the CD, APY, and compound interest calculators were sending the values entered to Google Analytics along with a usage event. They now record only that a calculation was run, with no figures.
September 2026 — Site pages (content). The about page said sales tax is broken out separately for every state; since September 23 all states are compared on one page. This page said secondary sources are never cited; a few figures with no government source (mortgage and CD rate surveys, average local sales tax rates, a homebuyer survey) are, and are now named as such. The net worth calculator's formula listed a cash field it doesn't have and left out HELOCs, personal loans, and other real estate. The hourly, salary, and overtime calculators now carry the Methodology & Sources panel this page promises, as do the DRIP and cost of living calculators.
September 2026 — Cost of living calculator (data). City price indexes were a blend of several sources that could not be traced to any one published figure. They are replaced with the Bureau of Economic Analysis's 2024 Regional Price Parities for 387 metro areas, with housing rents, goods, utilities, and other services shown separately. Some results change noticeably; for example, the Albuquerque area was listed at 89 and is 95.5 in BEA's data.
September 2026 — Pay and everyday pages (content). The overtime page said overtime gets no special tax treatment; for 2025 through 2028 the required overtime premium can be deducted, up to $12,500 a year ($25,000 joint). The hourly and salary pages counted 10 federal holidays; there have been 11 since 2021. The net worth page presented Fidelity's retirement-savings guideline as a net worth benchmark, and the tip page had two tipping guides that contradicted each other.
September 2026 — Savings and inflation pages (content). The inflation page said a 1980 dollar is worth about $3.70 today; at 2025 prices it is about $3.91. It dated the 13.5% inflation peak to 1979 (it was 1980) and called it the worst in peacetime history (1947 was higher). It also described the 2026 figure as an estimate from the year-over-year rate; it is the August 2026 index reading. The savings goal page twice called a 6–7% after-inflation return "conservative"; that is roughly the long-run average for stocks. The savings hub said the 401(k) calculator models fees; it does not.
September 2026 — Sales tax notes (content). Mississippi was described as taxing groceries at the full 7%; since July 1, 2025 the rate on SNAP-eligible food is 5%. Connecticut's tax on meals was given as 7.75%; it is 7.35%, and 7.75% is the rate on luxury goods. Idaho's food tax credit was given as $120; it is $155 per person from 2025. Florida's county surtaxes were described as capped at 1.5%; they run up to 2%. West Virginia's 1% municipal sales tax was attributed to "a few" cities, and Vermont's 1% local option to "most" cities; many West Virginia municipalities levy it, and 36 Vermont towns do. State and average local rates for all 51 jurisdictions match the Tax Foundation's July 1, 2026 table.
September 2026 — Sales tax holidays and grocery note (content). Connecticut's clothing holiday was described as covering items under $100; the limit is under $300. Florida was said to hold hurricane-preparedness and Freedom Week holidays; neither is on its 2026 schedule. Mississippi's back-to-school holiday was placed at the end of July; in 2026 it ran July 10–12. Alabama was described as taxing groceries at 3% on the way to 2%; the state rate fell to 2% on September 1, 2025.
September 2026 — 401(k) and retirement calculators (calculation). The 401(k) calculator did not apply the IRS contribution limits it described: a $300,000 salary at a 15% deferral added $45,000 a year, not the $24,500 limit. It now caps deferrals at $24,500 plus the catch-up for your age ($8,000 at 50, $11,250 at 60 to 63) and the combined employer and employee total at $72,000. The retirement calculator grew your income need for inflation but left Social Security in today's dollars, overstating the savings you would need; both are now grown by inflation, and the return is entered before inflation to match. The DRIP page said reinvesting typically adds 30–50% after 15 to 20 years; at a 2% yield and 6% price growth it is about 21% after 20 years.
September 2026 — Loan and debt pages (calculation and content). The auto loan calculator taxed the full vehicle price even when you entered a trade-in; most states tax the price after the trade-in, which is now the default, with an option for states such as California that do not. The loan comparison page's examples were wrong: $20,000 at 8% over 84 months costs $6,185 in interest, not $6,100, and $3,623 more than a 36-month loan, not $3,528; its origination-fee example understated interest by $22 to $33. The student loan page still listed the SAVE plan, which ended on July 1, 2026, and did not describe the Repayment Assistance Plan or the tiered Standard plan for new loans. The debt payoff page had its optimistic and pessimistic minimum-payment advice reversed. The balance transfer page said you generally cannot transfer to a card you already have; you can, just not between two cards from the same issuer.
September 2026 — Mortgage refinance and payment calculators (calculation). The refinance calculator's "net over your holding period" counted only the lower payments, less closing costs. When a refinance restarts the term, part of the lower payment is slower paydown. Refinancing $250,000 at 7% with 22 years left into a 30-year loan at 6% showed $15,581 saved over five years; after the $11,289 larger balance you still owe, it is $4,292. The mortgage payment calculator's yearly schedule charged PMI on the shrinking balance while the monthly figure used the original loan amount; both now use the original loan amount, as PMI is billed.
September 2026 — Mortgage and housing pages (content). The mortgage payment page told readers to enter their APR; the payment is figured from the interest rate, and the APR overstates it. The home affordability page described 43% as the qualified-mortgage cap that most conventional loans stop at; that limit was replaced in 2021, and Fannie Mae allows up to 50% through automated underwriting. It also said FHA mortgage insurance lasts the life of every loan (it ends after 11 years with at least 10% down) and put the median first-time buyer down payment at 6–8% (NAR's 2025 profile says 10%). The down payment page said PMI cancels automatically at 80% of the original value; that is when you can request it, and it ends automatically at 78%. The home equity page said FHA cash-out refinances can exceed 80% of value; they cannot. The refinance page gave half-point savings as the savings from a full point, and its advice for modeling financed closing costs raised the current loan's balance as well as the new one's.
September 2026 — State pages and state hubs (content). City lists on the state paycheck pages used rounded 2023 figures and several were out of order or missed a larger city (Mobile, Alabama; Gilbert, Arizona; Fresno, California; Macon, Georgia; Carmel, Indiana; Fort Worth, Texas, among others). They now show the largest cities from the Census Bureau's estimates for July 1, 2025. The state paycheck hub said New Hampshire's interest and dividends tax was being phased out; it was repealed starting with 2025. It listed Maryland among states with paid-leave deductions, which do not start there until 2027, left out Delaware, Maine and Minnesota, and said a $100,000 earner pays more than $7,000 in state tax in California or New York; it is about $5,100 and $4,900. The state rate table named only Arizona for the lowest top rate; North Dakota ties it at 2.5%.
September 2026 — CD ladder calculator (calculation). The comparison with a single CD set the ladder's interest, with rungs held one to five years and then left idle, against a single CD held the full five years. Most of the gap it reported was money the ladder was not invested for. Both are now valued at the same date, with early rungs reinvested at today's rates. With September 2026 rates, a $50,000 five-rung ladder comes out about $261 ahead of one 5-year CD, not $4,416 behind.
September 2026 — CD calculator and term pages (calculation and content). The early-withdrawal estimate never showed less than the original deposit, although a penalty larger than the interest earned can reduce principal. The 3-year CD page said $10,000 at 4.50% grows to about $14,117; it is $11,411.66. It also gave the 2026 IRA limit as $7,000; it is $7,500. The 2-year page said a 2-year CD earns about $470 more than two back-to-back 1-year CDs at the same rate, and the 5-year page made a similar claim; at the same rate they earn exactly the same. The $100,000 page put 5-year interest at a 4.75% APY at $26,109; it is $26,116.
September 2026 — Bonus tax calculator (calculation). The aggregate method computed the extra annual tax the bonus causes, not what payroll withholds. IRS Publication 15 has the employer add the bonus to one regular paycheck and withhold as if that paycheck were normal pay, which annualizes the bonus. On a $60,000 salary paid every two weeks, a $10,000 bonus is withheld about $2,697 under the aggregate method, not the $1,550 the calculator showed. The calculator now asks how often you are paid, follows the Publication 15-T percentage method, and separately shows what the bonus adds to your tax.
September 2026 — Self-employment and income tax (calculation). Neither calculator applied the Schedule SE rule that net earnings under $400 owe no SE tax. When you also had wages above the Additional Medicare Tax threshold, the self-employment calculator charged the 0.9% on those wages as well; Form 8959 charges self-employment income only above the threshold left after wages. The income tax calculator charged Additional Medicare Tax on all income, including interest and other non-wage income, which overstated tax by 0.9% of that income above the threshold. The self-employment page also said your own health insurance and retirement contributions reduce SE tax; they reduce income tax only.
September 2026 — 2026 federal brackets (data). The head of household 32% bracket began at $201,775, the single filer figure. Rev. Proc. 2025-32 sets it at $201,750, so head of household estimates in that range were up to $2 low. The projected 2027 figure for the same threshold moves from $208,225 to $208,200.
September 2026 — Income tax and paycheck pages (content). The income tax page gave the 2026 cap on the state and local tax deduction as $40,000; it is $40,400, reduced above $505,000 of income, and the higher cap started in 2025, not 2026. Its worked example's effective rate was 13.2%, not about 14%. The paycheck page's list of states with disability or paid-leave deductions left out Delaware, Maine and Minnesota and included Puerto Rico. Three hub pages listed nine flat-rate states, including Massachusetts; there are 15, and Massachusetts is not one. The payroll hub said San Francisco has a local income tax; it does not.
September 2026 — 2027 tax figures (content). The 2027 page said HSA limits were not yet published; Rev. Proc. 2026-24 already sets them at $4,500 self-only and $9,000 family, and they are now listed. It also understated how far apart the two ways of handling the missing October 2025 inflation reading are: up to about $950 at the top thresholds, not $150.
September 2026 — Vermont income tax and paycheck (data). Vermont estimates for 2025 used the 2024 brackets, standard deduction ($7,400 single), and exemption ($5,100). The 2025 amounts are $49,400 / $119,700 / $249,700 single brackets, a $7,650 deduction, and a $5,300 exemption, from the Department of Taxes' 2025 rate schedules and IN-111 instructions; the old figures overstated tax by about $78 at $80,000. Take-home pay also now includes the Child Care Contribution employers may deduct, up to 0.11% of wages.
September 2026 — Alaska paycheck (data). Alaska take-home pay left out the employee unemployment insurance contribution, 0.5% of wages up to $51,700 for 2025 and $54,200 for 2026, overstating take-home pay by up to $258.50 and $271. It is now deducted, from the Department of Labor and Workforce Development's rate tables. The Alaska summary also wrongly called it the only state without either an income or a statewide sales tax; New Hampshire has neither too.
September 2026 — Delaware income tax (calculation). Delaware estimates left out the $110 personal credit per exemption ($220 on a joint return with no dependents), overstating tax by that amount. Brackets and the standard deduction were correct. Corrected from the 2025 PIT-RES instructions, with tests.
September 2026 — Rhode Island income tax (data and calculation). 2026 Rhode Island estimates reused the 2025 brackets, standard deduction, and exemption instead of the indexed 2026 amounts ($82,050 and $186,450 brackets, $11,200 deduction, $5,250 exemption). Neither year phased out the deduction and exemptions, which fall 20% for each $7,250 of income above $254,250 for 2025 ($7,450 above $261,000 for 2026); that understated tax for filers above those levels by up to about $960 for 2025 and $985 for 2026. Corrected from the Division of Taxation's Advisory 2025-22, with tests.
September 2026 — Montana 2027 projection (data). The 2027 Montana projection used the 2026 rates. HB 337 (2025) already sets 2027: 4.7% up to $65,000 of taxable income for single filers ($130,000 joint) and 5.4% above. The old projection was about $156 too high at $80,000. 2025 and 2026 figures were correct.
September 2026 — Maine income tax and paycheck (data and calculation). Maine estimates didn't phase out the standard deduction or personal exemption for higher incomes, which understated tax by up to about $1,070 for a single filer at $175,000 of income. The 2026 figures also kept 2025's brackets and $5,150 exemption, and lacked the new 2% surcharge on taxable income over $1 million ($1.5 million joint). All corrected from Maine Revenue Services' 2025 and 2026 rate schedules and 2025 Form 1040ME instructions, with tests.
September 2026 — Hawaii income tax and paycheck (data). 2026 Hawaii estimates used the 2025 standard deduction of $4,400 ($8,800 joint). Act 46 (2024) raises it to $8,000 ($16,000 joint) for 2026, which overstated 2026 tax for a single filer by about $274 at $80,000. The 2027 projection now also uses Act 46's wider 2027 brackets. Separately, the 2025 Temporary Disability Insurance cap was $7.21 a week ($374.92 a year), not the 2026 figure of $7.50. Corrected from Act 46 and the Department of Labor and Industrial Relations' 2025 and 2026 wage base notices, with tests.
September 2026 — West Virginia income tax and paycheck (data). 2026 West Virginia estimates still used the 2025 rates of 2.22% to 4.82%. SB 392, signed March 31, 2026 and retroactive to January 1, cut every rate by 5%, to 2.11% to 4.58%. The old rates overstated 2026 tax for a single filer by about $146 at $80,000. Corrected from the Tax Division's rate-cut page and March 2026 withholding tables, with tests.
September 2026 — Nebraska income tax and paycheck (data). Nebraska estimates left out the personal exemption credit, $171 per exemption for 2025 and $176 for 2026, which comes off the tax. Brackets, rates, and the standard deduction were already correct. The omission overstated tax by $171 to $176 for a single filer and twice that on a joint return. Corrected from the Department of Revenue's tax rate chronology and 2025 Form 1040N instructions, with tests.
September 2026 — Idaho income tax and paycheck (data). 2026 Idaho estimates applied 5.3% from the first dollar of taxable income, dropping the zero-rate threshold ($4,811 single, $9,622 joint for 2025) that Idaho Code 63-3024 keeps every year. This overstated 2026 tax by about $255 for single filers above the threshold. The $10 permanent building fund tax that every filer owes was also missing. Both are corrected, with tests; the 2025 threshold is used for 2026 until the indexed amount is published.
September 2026 — New Mexico income tax and paycheck (data). New Mexico estimates left out the low- and middle-income exemption: up to $2,500 per exemption, reduced by 15% of AGI over $20,000 for single filers (10% over $30,000 joint) and gone at $36,667 or $55,000. This overstated tax for lower-income filers by up to about $63 single and $79 joint. Corrected from the 2025 PIT-1 instructions, with tests.
September 2026 — Connecticut personal exemption (calculation). The Connecticut exemption phase-out was applied as a straight line; the return reduces it by $1,000 for each $1,000 of income or part of $1,000, so it is gone above $44,000 single, not $45,000. The calculator now follows the steps, a difference of at most about $50.
September 2026 — Mississippi income tax and paycheck (data). The 2026 and 2027 Mississippi rates were applied from the first dollar of taxable income. House Bill 1 (2025) lowers the rate only on income above $10,000; the first $10,000 stays at 0%. This overstated 2026 tax by $400 for anyone with more than $10,000 of taxable income, and 2027 projections by $375. Corrected from the Department of Revenue's 2026 withholding publication (89-700), with tests.
September 2026 — Arkansas income tax and paycheck (data and calculation). Arkansas estimates applied the high-income table (2% on the first $4,500, then 3.9%) to every income and used last year's $2,410 standard deduction. Most filers use the regular table, which untaxes the first $5,599 and has 2%, 3%, and 3.4% bands below the top rate; the standard deduction is $2,470; each filer gets a $29 personal tax credit; and Act 2 of the 2026 First Extraordinary Session cut the top rate to 3.7% for 2026. Together these overstated tax for a single filer at $80,000 by about $366 for 2025 and $468 for 2026. The calculator now follows the regular table, the high-income table, and the bracket adjustment between them, matching the 2025 AR1000F tax table within about a dollar, with tests.
September 2026 — Iowa income tax and paycheck (data). Iowa estimates applied the 3.8% rate to all income. Since 2023 the Iowa return starts from federal taxable income, so the federal standard deduction ($15,750 for 2025, $16,100 for 2026) comes off first, and a $40 personal exemption credit ($80 joint) comes off the tax. Leaving both out overstated 2026 Iowa tax for a single filer by about $652 at $80,000. Corrected from the Department of Revenue's 2025 IA 1040 expanded instructions, with tests. The school district surtax is still not included.
September 2026 — Utah income tax and paycheck (data and calculation). Utah estimates used the 2024 rate of 4.55% for both 2025 and 2026. The rate is 4.5% for 2025 and 4.45% for 2026 under SB 60. They also left out the taxpayer tax credit, which Utah gives in place of a standard deduction: 6% of the federal standard deduction, reduced by 1.3% of income above a base amount. Together these overstated 2026 Utah tax for a single filer by about $723 at $40,000 and $243 at $80,000. Both are corrected from the Tax Commission's 2025 TC-40 instructions and the enrolled SB 60, with tests.
September 2026 — Connecticut income tax and paycheck (calculation). Connecticut estimates applied the rate schedule and the personal exemption phase-out, but not the three adjustments on the CT-1040 tax calculation schedule: the 2% phase-out add-back, the tax recapture, and the personal tax credit. For a single filer this overstated tax by about $133 at $40,000 and understated it by $125 at $80,000 and $2,300 at $300,000. All three are now applied from Tables C, D, and E of the 2025 CT-1040 instructions, which the 2026 withholding rules leave unchanged, with tests.
September 2026 — Oregon income tax and paycheck (data and calculation). Oregon estimates were missing three things. The subtraction for federal income tax, up to $8,500 for 2025 and $8,750 for 2026 and phased out for high earners, was not applied, nor was the personal exemption credit ($256 for 2025, $263 for 2026). The standard deduction and 2026 brackets were also a year behind. Together these overstated Oregon tax by about $1,050 at $80,000 for a single filer. Separately, the 0.1% statewide transit tax was left out of take-home pay. All are corrected from the Department of Revenue's 2025 and 2026 withholding formulas, with tests.
September 2026 — Louisiana income tax (data). 2026 Louisiana estimates used the 2025 standard deduction of $12,500 ($25,000 joint). It is indexed from 2026, and the Department of Revenue's 2026 withholding tables use $12,875 ($25,750). Tax was overstated by about $11 for a single filer. Updated, with a note that the final figure may differ slightly.
September 2026 — Alabama and Missouri income tax (calculation). Both states let you deduct federal income tax, and the calculators ignored it. Alabama deducts all of it, and Missouri a share that falls from 35% to 5% as income rises, capped at $5,000 ($10,000 combined). Alabama's standard deduction, which shrinks from $3,000 to $2,500 (single) and from $8,500 to $5,000 (joint) as income rises from $26,000 to $35,500, was also applied at its maximum. Net of both, Alabama tax was overstated by about $413 at $80,000 for a single filer, and Missouri's by about $62. Both are now modeled, with tests.
September 2026 — South Carolina income tax (calculation). 2026 South Carolina estimates gave every filer the full $15,000 ($30,000 joint) South Carolina Income Adjusted Deduction. Under H. 4216 it shrinks as federal AGI rises above $40,000 single ($80,000 joint) and is gone at $95,000 ($190,000). Tax was understated by up to about $780 for a single filer; at $80,000, by about $570. The phase-out is now applied, with tests.
September 2026 — Minnesota income tax (data and calculation). 2026 Minnesota estimates used the 2025 brackets and standard deduction. The Department of Revenue's 2026 inflation-adjusted amounts move the brackets up 2.369% and the standard deduction to $15,300 ($30,600 joint); tax fell by about $34 at $80,000. The calculators also gave high earners the full standard deduction, which Minnesota cuts by 3% of AGI over $244,400 and 10% over $337,800, up to 80%; that is now applied. Paid Leave is now capped at the Social Security wage base ($184,500) rather than $185,000. Corrected with tests.
September 2026 — Wisconsin income tax (data and calculation). Two errors. The brackets did not reflect 2025 Wisconsin Act 15, which widened the 4.4% bracket to $50,480 ($67,300 joint) for 2025, and 2026 carried the 2025 figures instead of the indexed 2026 ones. And the calculators gave every filer the full standard deduction, although Wisconsin's shrinks by 12% of income over $20,120 for a single filer in 2026 (19.778% over $29,040 joint) and is gone by about $136,000. The net effect was to understate Wisconsin tax for most full-time earners: the $80,000 single estimate rises by about $150. Corrected from the Department of Revenue's 2025 and 2026 Form 1-ES schedules and the 2025 Form 1 instructions, with tests.
September 2026 — Colorado paycheck (data). 2026 Colorado paycheck estimates used the 2025 FAMLI employee share of 0.45%. The FAMLI Division lowered the total premium to 0.88% for 2026, so the employee share is 0.44%, and take-home pay was understated by $7.50 at $75,000. Corrected, with tests.
September 2026 — Maryland paycheck and income tax (data and calculation). The Maryland county rates in the paycheck calculator were one to two years out of date. Calvert, St. Mary's, and Allegany were too low (3.00% or 3.05% instead of 3.20%), Dorchester and Kent too low (3.20% instead of 3.30%), and Cecil and Washington too high (3.00% instead of 2.74% and 2.95%). Anne Arundel and Frederick were treated as single flat rates, but both now set rates by income; Anne Arundel county tax was overstated by about $170 at $75,000. Rates are now kept by year from the Comptroller's 2025 resident booklet and 2026 Withholding Tax Facts, with tests. Separately, the calculators gave every filer the full $3,200 personal exemption. Maryland reduces it above $100,000 of federal AGI ($150,000 joint) and removes it above $150,000 ($200,000 joint), so state tax was understated for higher earners, by about $176 for a single filer above $150,000. The phase-out is now applied.
September 2026 — Missouri income tax (data). 2026 Missouri estimates used the 2025 brackets. Missouri indexes them, and for 2026 each band is $1,348 wide, with the 4.7% top rate starting at $9,436 instead of $9,191. Tax was overstated by about $5 for most full-time earners. Corrected from the Department of Revenue's 2026 withholding formula, with tests. Missouri's separate taxation of each spouse on a combined return is not modeled, and the Missouri pages say so.
September 2026 — Massachusetts income tax (data). 2026 Massachusetts estimates applied the 4% surtax above the 2025 threshold of $1,083,150 instead of the 2026 threshold of $1,107,750, overstating tax by up to $984 for filers above it. Corrected from the Department of Revenue's surtax page, with tests. The paid family and medical leave rate was marked as unconfirmed for 2026; the Department of Family and Medical Leave confirms the employee maximum stays at 0.46%.
September 2026 — Washington paycheck (data). The paycheck calculator left out the WA Cares long-term care premium, 0.58% of all wages with no cap, which Washington employers have withheld since July 2023. Take-home pay was overstated by that amount: $435 a year at $75,000. It is now included with the paid family and medical leave premium; workers with an approved exemption should add it back. The Washington pages also now note the 9.9% tax on income over $1 million that takes effect in 2028.
September 2026 — Virginia income tax (data). Virginia estimates for 2025 and 2026 used a standard deduction of $8,500 ($17,000 joint). Legislation in 2025 raised it to $8,750 ($17,500 joint) for both years, so Virginia tax was overstated by $14.38 for a single filer and $28.75 for a joint return. 2027 projections now use the $9,200 ($18,400 joint) deduction enacted in the 2026 Appropriation Act. Corrected from Virginia Tax's 2025 Form 760 instructions and 2026 Legislative Summary, with tests.
September 2026 — New Jersey paycheck and income tax (data and display). The paycheck calculator left out the unemployment and workforce fund contributions New Jersey takes from workers' pay: 0.425% of the first $44,800 of wages in 2026 (up to $190.40) and of the first $43,300 in 2025 (up to $184.02). Take-home pay was overstated by up to that amount. It is now included with TDI and FLI, at the rates on the Department of Labor's rate table. The New Jersey bracket tables, here and on the state income tax rates page, paired joint-filer ranges with the wrong rates from $50,000 up, because New Jersey's joint schedule has a 2.45% bracket the single schedule doesn't. They also showed 5.525% as 5.53%. Both are fixed. The old New Jersey page text said TDI had been employer-funded since 2023; workers pay 0.19% in 2026. That text has been replaced.
September 2026 — Georgia (display). A note under the Georgia bracket tables still said the 2026 rate had stayed at 5.19%, after the tables themselves had been corrected to HB 463's 4.99%. The note now describes HB 463.
September 2026 — Michigan income tax (data). 2026 Michigan estimates used the 2025 personal exemption of $5,800 instead of the 2026 figure of $5,900 from the Treasury's 2026 withholding guide, overstating tax by $4.25 per exemption. Corrected. The 4.25% rate was already right.
September 2026 — Georgia income tax (data). 2026 Georgia estimates used a 5.19% rate and a $12,000 standard deduction, and our notes said the scheduled 2026 cut had not happened. That was true on January 1, but HB 463, signed in May 2026 and retroactive to the start of the year, set the rate at 4.99% and raised the standard deduction to $15,000 ($30,000 joint). Georgia tax for 2026 was overstated by $275.70 for a single filer earning $75,000. Corrected from the Department of Revenue's revised 2026 Employer's Withholding Tax Guide, and the notes rewritten.
September 2026 — Ohio income tax (calculation). The calculators gave every Ohio filer the $2,400 personal exemption. Ohio sets it by modified adjusted gross income: $2,400 at $40,000 or less, $2,150 up to $80,000, $1,900 up to $749,999, and nothing above that. Ohio tax was therefore understated above $40,000: by $6.88 for a single filer at $75,000 and $13.75 at $100,000. Now follows the tiers in the Department of Taxation's 2025 IT 1040 instructions, with tests.
September 2026 — Illinois income tax (data and calculation). 2026 Illinois estimates used the 2025 personal exemption of $2,850 instead of the 2026 figure of $2,925, overstating tax by $3.71 per exemption. The calculators also allowed the exemption at every income, but Illinois disallows it entirely above $250,000 of federal AGI ($500,000 joint), so tax above that line was understated by about $145 for a single filer. Both corrected from the Department of Revenue's Informational Bulletin FY 2026-15 and the IL-1040 instructions, with tests for each case.
September 2026 — Philadelphia wage tax (data). The Pennsylvania paycheck calculator used Philadelphia's July 2024 wage tax rates, 3.75% for residents and 3.44% for nonresidents. The city has cut the rate twice since, to 3.74% and 3.43% on July 1, 2025 and 3.735% and 3.425% on July 1, 2026. Now uses the current rates from the city's Department of Revenue; the tax on a resident earning $75,000 falls by $11.25 a year.
September 2026 — New York income tax and Paid Family Leave (data). 2026 New York estimates used 2025 tax rates. New York cut its five lowest bracket rates by about a tenth of a point for 2026 (to 3.9%, 4.4%, 5.15%, 5.4%, and 5.9%), so 2026 state tax was overstated: by $67 for a single filer earning $75,000. Paycheck estimates also used the 2025 Paid Family Leave rate, 0.388% capped at $354.53, instead of the 2026 rate of 0.432% capped at $411.91, understating the deduction by $33 at $75,000. Both corrected from the Department of Taxation and Finance's 2026 IT-2105 instructions and New York Paid Family Leave. Separately, the calculators do not yet apply New York's tax benefit recapture above $107,650 of New York AGI; the New York pages now say so.
September 2026 — California income tax (data and calculation). Every calculator using California income tax had two errors. The standard deduction was the 2024 figure, $5,540 single and $11,080 joint, instead of the 2025 figure of $5,706 and $11,412, and it carried into 2026 as well. Separately, California's personal exemption credit, $153 per filer ($306 joint) and phased out at high incomes, was not applied at all, so California tax was overstated for nearly everyone: by $168.43 for a single filer earning $80,000. Several joint-filer bracket thresholds were also off by $2. All corrected against the Franchise Tax Board's 2025 rate schedules and Form 540, and checked against hand-computed values in our test suite. The 1% tax on income over $1 million is now called by its current name, the Behavioral Health Services Tax.

Earlier corrections

September 2026 — Retirement Calculator (calculation). Monthly compounding used the nominal convention, dividing the annual return by twelve. That is correct when a compounding frequency is specified — our compound interest calculator asks for one — but this page asks only for an annual return, and 7% divided by twelve compounds to 7.229% a year rather than 7%. A 30-year projection was overstated by roughly 5%: $1,019,369 against a correct $968,645 on the default inputs. It also disagreed with our 401(k) calculator, which has always used the effective monthly rate for the same input. Both pages now return identical figures for identical inputs. Projections shown before September 14, 2026 were too high; the required-monthly-contribution figure was correspondingly too low.
September 2026 — Capital Gains Tax Calculator (calculation). Long-term gains were not stacked on top of ordinary income. The preferential rate was looked up at income excluding the gain and then applied to the whole gain, so a gain that should have straddled the 0% and 15% bands was taxed entirely at the lower one. A single filer with $40,000 of income and a $60,000 long-term gain was shown $0 of tax; the correct figure is $7,582.50. Short-term gains had the same flaw, taking a single marginal rate rather than spanning brackets. Separately, the 3.8% Net Investment Income Tax tested income before the gain against its threshold — but the gain counts toward that threshold — so it was missed entirely for some filers, and it was never applied to short-term gains at all. All four corrected, and the calculator now shows the blended rate across the gain rather than a single band. If you used this page before September 13, 2026 and your gain spanned more than one bracket, re-run it.
September 2026 — Self-Employment Tax Calculator (calculation). The 0.9% Additional Medicare Tax was charged against gross net profit rather than net earnings from self-employment, which are 92.35% of profit. This overstated the surtax for everyone above the threshold — $900 instead of $693.45 on $300,000 of profit. Corrected. The rest of the calculation, including the 92.35% adjustment itself and the Social Security wage-base coordination with W-2 wages, was unaffected.
September 2026 — Mortgage Payment Calculator (calculation). The amortization schedule charged private mortgage insurance for the entire loan term. Under the Homeowners Protection Act, PMI terminates automatically once the balance reaches 78% of the original property value. On a $475,000 loan against a $500,000 home the schedule showed $79,850 of PMI against a correct $43,116 — about $36,700 of cost that would never be paid, making a low-down-payment purchase look worse than it is. The headline monthly payment and total-interest figures were not affected; only the year-by-year schedule was.
September 2026 — Debt Payoff Calculator (calculation). The "interest saved" figure compared against a minimum-payments-only baseline that was never checked for whether it actually cleared the debt. When a minimum payment is at or below the monthly interest the balance never falls, so the comparison simply accrued interest to its 50-year horizon — producing, in one case, $117,142 of "savings" on $12,000 of debt. It now reports that the debt never pays off at those minimums, which is the more useful answer. The payoff projection itself was correct throughout.
September 2026 — CD Calculator (documentation). The early-withdrawal row was labelled as what you would receive for breaking the CD early, but the figure shown was the full maturity value minus the penalty — a number nobody receives by withdrawing early, since less interest would have accrued by then. The penalty amount itself was correct. Relabelled to "Maturity Value Less Penalty", with a note that breaking sooner returns less.
September 2026 — Rent vs. Buy Calculator (documentation). The published formulas described a simpler model than the calculator runs. They credited investment opportunity cost only to the renter's avoided down payment, when in fact the model is symmetric: whichever side has the lower monthly outlay invests the difference, and both sides compound. The calculations were correct; the methodology understated them. Rewritten to match, including a note that a "true cost" can legitimately come out negative when investment growth exceeds what was paid out.
August 2026 — Kentucky paycheck and income tax (data). Kentucky's 2026 standard deduction was carried over from 2025 ($3,270) instead of the amount the Kentucky Department of Revenue announced for 2026 ($3,360), which slightly overstated Kentucky state tax. Corrected to $3,360 single / $6,720 married filing jointly.
August 2026 — Georgia rate note (documentation). The rate note on Georgia pages described the 2026 flat-rate reduction as having taken effect. It did not — the statutory revenue triggers were not met, so the rate stayed at 5.19%. The calculators used the correct 5.19% throughout; only the explanatory note was wrong. Rewritten.
August 2026 — Capital Gains Tax Calculator (documentation). The methodology panel's "what changed this year" note listed the 2025 long-term thresholds ($48,350 / $533,400) under the 2026 heading. The calculator's math and the on-page 2026 rate table were correct — only the note was wrong. Updated to the 2026 figures ($49,450 / $545,500).
July 2026 — Inflation Calculator (data). The 2022 entry in our CPI-U table used the December 2022 index (296.8) instead of the 2022 annual average (292.7), which overstated inflation by roughly 1.4% for any calculation spanning 2022. The 2024 and 2025 annual averages were also corrected to final BLS figures (313.7 and 321.9). Note that 2025 remains provisional: October 2025 CPI was never published because of the 2025 lapse in appropriations, so that year's average is based on available months.

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Updates to this document

Last reviewed: September 2026. This page is updated whenever our process changes materially — new review steps, new source standards, or new disclosure obligations.