TakeHomeFacts

How we calculate

Every calculator on TakeHomeFacts is a thin screen over one open calculation engine. The engine reads versioned rate files, one per country and tax year, and each rate in a file carries the URL of the official document it came from. The page you are reading the result on renders its sources list from that same file, so a rate cannot change without its source changing with it.

United States

Federal income tax. We compute the year's tax from the 2026 standard deduction and brackets published in IRS Rev. Proc. 2025-32 (single 16,100, married filing jointly 32,200, head of household 24,150), subtract W-4 Step 3 credits, and divide by the number of pay periods. This is the annual-liability method. Employers withhold with the percentage-method tables in Publication 15-T, which spread the same yearly tax across paychecks but can differ by a few dollars per period, more so with Step 2 (two jobs) checked. We show the method on every result and are adding the 15-T tables as a second mode.

FICA. Social Security at 6.2% of wages up to the SSA wage base (184,500 in 2026). Medicare at 1.45% of all wages. Additional Medicare at 0.9% once wages in the year pass $200,000, which is the withholding threshold regardless of filing status. Section 125 deductions (health, dental, vision premiums, HSA and FSA through a cafeteria plan) reduce FICA wages. 401(k) contributions do not.

States. Each state is one of three kinds: no wage tax, a flat rate with an exemption or standard deduction, or brackets. Brackets, standard deductions and exemption amounts for 2026 come from the Tax Foundation's compilation as of 1 January 2026 and are cross-checked against the state's own withholding publication before a state page goes live. State disability or paid leave payroll deductions are modelled where they exist (California SDI, and the PFML programmes of several states). City taxes are modelled with their own brackets where a city levies them.

United Kingdom

All 2026/27 figures come from GOV.UK's "Rates and thresholds for employers 2026 to 2027" (retrieved 25 October 2026). Income tax is computed on earnings above the personal allowance (tapered by £1 for every £2 above £100,000), using the England/Wales/Northern Ireland bands or the six Scottish bands. National Insurance uses the category letter's rates between the primary threshold and the upper earnings limit and above it. Student loans are 9% (postgraduate 6%) of earnings above the plan threshold. Pensions: net pay and salary sacrifice contributions reduce taxable pay. Salary sacrifice also reduces NI and student-loan earnings. Relief at source contributions show the 80% you pay. Figures are annual. In-year PAYE is cumulative and can differ month to month.

VAT

Add VAT: gross = net x (1 + rate). Remove VAT: net = gross divided by (1 + rate). Rates for 31 countries are in one file with a per-country verification status. EU rates are checked against the Commission's Taxes in Europe Database and each national authority before that country's page is published.

Rounding

The engine computes in full precision and rounds only what is displayed, half away from zero to the nearest cent or penny, the convention of payroll software. Per-period figures are the annual figure divided by the number of periods, rounded once.

Update calendar

Every change is a dated entry in the changelog and re-runs the accuracy tests.