How every figure on this site is computed

One rule applies to all eight markets: no number is interpolated from an average, and no number is borrowed from another country's table. Each market has its own dataset, its own engine and its own published sources. Below is the chain, market by market, including the parts that are deliberately not modelled.

United States

Gross pay goes through four separate stacks, in this order: pre-tax 401(k) deferral, federal income tax on the remaining wages (2026 brackets and standard deduction, single or married filing jointly), FICA (6.2% Social Security up to the wage base, 1.45% Medicare, plus the additional 0.9% above the threshold), then the state stack. Twenty-nine states have a flat or graduated income tax on top; the nine with no wage tax show zero. City and county taxes that exist as a real line on a pay stub — New York City, Philadelphia, Detroit, Columbus and the like — are applied where the calculator lets you pick them.

Not modelled: itemised deductions, credits other than the standard deduction, multi-state telecommuting splits, and state-specific quirks that apply to a few thousand filers.

United Kingdom

PAYE applies the personal allowance, then the basic, higher and additional bands, with the Scottish and Welsh income tax schedules available as a separate route because Scotland taxes income differently from the rest of the UK. National Insurance is Class 1 employee contributions on earnings between the primary threshold and the upper earnings limit, and the 2% rate above it. Student loan repayments are a separate deduction with their own thresholds (Plan 1, 2, 4, 5 and postgraduate), not a tax. Workplace pension contributions are modelled both as net pay arrangements and as relief at source, because those two arrangements change the annual figure differently.

Canada

Federal tax with the basic personal amount, then the provincial or territorial schedule for the selected province; CPP and CPP2 with the year's maximum contributory earnings, and EI at the employee rate with its own ceiling. The payroll deduction tables published by the CRA (T4032 guides) are the cross-check for the basic personal amounts used per province. Quebec is modelled in the same engine on its own parameters: QPP (6.3% up to $74,600) and QPP2 (4% to $85,000) replace CPP, QPIP at 0.43% is added for parental insurance, EI runs at the reduced Quebec rate of 1.3%, and the federal tax — after the basic personal credit — is cut by the 16.5% Quebec abatement. The provincial schedule is Revenu Québec's four bands with its $18,952 basic credit, verified against CRA T4032-QC and Revenu Québec's 2026 parameter publication.

Australia

Resident tax brackets including the 15% bracket that starts on 1 July 2026, the Medicare levy and its low-income reduction, the Medicare levy surcharge where the income threshold is crossed, then HELP or other study loan repayments. Superannuation guarantee is employer money and is shown separately — it is not part of take-home pay. Casual loading is modelled as a 25% uplift on the hourly rate so the page can show what the loading is actually worth after tax.

Germany

The income tax is not a bracket table but the formula in §32a EStG: a free allowance, then two quadratic zones, then two linear rates. The Lohnsteuer depends on the Steuerklasse: classes I, II and IV apply the tariff directly (class II adds the single-parent allowance), class III splits the taxable amount in half, applies the tariff and doubles it, and classes V and VI use the separate annual formula in §39b Abs. 2 Satz 7 EStG — twice the difference between the 1.25-fold and 0.75-fold amount, with a 14% floor and the 14,071 / 34,939 / 222,260 euro breakpoints. Class VI gets neither the employee allowance nor the special-expenses allowance, because those belong to the main job.

Social insurance is five separate branches, each with its own ceiling: health and long-term care stop at the lower ceiling, pension and unemployment at the higher one. Class VI is still subject to all five. Solidarity surcharge is applied only above the exemption threshold, and church tax at 8% or 9% where selected.

One honest difference: official payroll withholds tax using the Vorsorgepauschale (a flat allowance for pension and health contributions), while this engine subtracts the actual employee contributions. For a statutory-insured employee the two bases differ by a few hundred euros a year, so the Lohnsteuer here can sit a little below the official Prüftabelle. The same convention is applied to every class, so comparisons between classes on this site remain internally consistent.

Taiwan

月薪先依投保金額分級表換成投保金額（不是直接用月薪），再算勞保、就業保險與健保的員工自付額； 年終獎金與其他非經常性給付超過一定金額時，另計二代健保補充保費。所得稅走綜合所得稅的年度級距與 累進差額，並套用薪資所得特別扣除額；婚姻與扶養情境會改變免稅額與扣除額合計。

未建模：各縣市不同的勞保職業災害費率、公司自提勞退比例（只算員工自提 0／3／6%），以及股利與 海外所得合併計稅的影響。

Mexico

月薪照 Anexo 8 的 ISR tarifa 逐檔累進，再減 subsidio para el empleo（以 UMA 月值換算，有收入上限）， 最後扣 IMSS 員工負擔：2.375% 的基礎費率，加上超過 3 UMA 部分的 0.400%。INFONAVIT 由雇主繳， 不從員工薪資扣。年度頁同時列出 aguinaldo 併入後的邊際稅額。

Brazil

INSS 按 faixas 逐段累進（7.5% 到 14%，上限為 teto），IRRF 走月度稅表並套用 redução mensal （Lei 15.270/2025 的減免），因此低薪段的實際扣繳可能為零。13º salário 以 exclusivo 表分開計算， 不與月度薪資合併。FGTS 是雇主繳的 8%，不進員工到手金額。

Rounding

Each market rounds where its own authority rounds. Germany floors the taxable amount to whole euros before applying §32a, because that is what the statute says. Brazil and Mexico work in monthly tables and are shown to the cent. The US and Canada are shown to the cent on withholding and rounded to the dollar in the annual summary. Where a site uses a published average rather than an individual rate — for example the German average Zusatzbeitrag of 2.9% — the page says so instead of hiding it.

Refresh policy

Every dataset carries a reviewed_at date and a data_status. When an authority publishes a new table mid-year — a new contribution ceiling, a changed surcharge, a new bracket — the dataset is edited first, the engine is re-run against the published example, and only then are the pages rebuilt. The sources page shows which documents each market currently rests on.

Anything marked as not modelled on a market page is excluded on purpose. It is not an oversight, and it is not replaced with an approximation that would look more precise than it is. Read the financial disclaimer before acting on a number.