Methodology

Every calculator on calcswiss.ch discloses how it calculates. On this page we document, for each tool, the formulas, the parameters used and their official sources, with the reference date.

Our principles

• Every figure has a source. Calculation parameters come from official publications (FTA, FSO, FOPH, cantonal tax administrations) and are versioned with their retrieval date.
• Tested formulas. Every tax formula is tested automatically against official example calculations before it goes live.
• We name the limits. Where a calculation simplifies (e.g. pension-fund contributions at the statutory minimum rather than regulatory values), this is stated with the relevant calculator.

Documentation per calculator

Salary calculator

The salary calculator deducts the statutory employee contributions from the gross annual salary: AHV/IV/EO (5.3%, no limit), ALV (1.1% up to CHF 148’200 per year), NBU (employer-dependent) and BVG (retirement credit on the coordinated salary, 7–18% by age, half the employee’s share). Rates and limit amounts as of 2026, sources: FSIO, ahv-iv.ch and the BVG key figures. Details and a worked example directly with the calculator.

Not included: income tax (assessed separately, or withholding tax) and voluntary contributions such as daily sickness benefits. NBU and BVG deductions depend on the employer and pension fund; the calculator uses the statutory minimum.

Cantonal tax comparison (26 cantons)

The cantonal tax comparison calculates, for each canton, the simple cantonal tax under the 2026 cantonal income-tax schedule and multiplies it by the canton and capital multipliers; added to this is the direct federal tax under the federal schedule. The data source is the official FTA tax data (swisstaxcalculator.estv.admin.ch). In cantons with their own municipal schedule (Schwyz, Sion) we use the official municipal schedule. Not included: church tax, personal taxes, wealth tax. The comparison is based on taxable income; cantonal differences in deductions are not reflected. The calculation logic is validated against the MIT-licensed reference implementation devbrains/swisstaxcalculator, which builds on the same FTA data.

Pillar 3a calculator

The pillar 3a calculator calculates income tax (the same method as the comparison) once without and once with the 3a deduction; the difference is the tax saving. Maximum amounts 2026 per the FSIO: CHF 7'258 with a pension fund, 20% of earned income or a maximum of CHF 36'288 without a pension fund.

Withholding tax calculator

The withholding tax calculator evaluates the cantons' official withholding-tax tariffs (FTA tariff files, “salaries” format) for all 26 cantons. The tariffs are based on the monthly gross salary; depending on the canton, tariff code (A/B/C/H), number of children and church-tax status, a separate rate applies. Covered are tariff codes A, B, C and H with 0–5 children; special cases (cross-border commuters, board members, replacement income) are not included. For an indicative calculation the rates are grouped to 0.05 points — the binding statement is produced by the employer under the cantonal tariffs, whose content is the cantons' responsibility.

The methodology of further calculators will appear here as they are published.

Data currency and update cadence

Tax and social-insurance parameters change annually. We update the data according to the following calendar — each figure carries an internal retrieval date that we keep with it on changes:

• Start of year: new tax year — FTA schedules and multipliers, AHV/ALV contribution rates, pillar 3a maximum amounts and BVG key figures are brought up to date.
• End of September: the approved health-insurance premiums of the Federal Office of Public Health (FOPH) appear — relevant for the planned franchise calculator.
• On publication of new withholding-tax schedules: update of the covered cantons.

Every tool-relevant figure is stored in versioned data files with source (official link),retrieved (retrieval date) and taxYear. The “Last updated” note shown on each calculator page corresponds to this retrieval date, not to the time of the last page build — we do not display artificial currency.

Known limits

So that you can interpret the results correctly, here are the main simplifications:

• Taxable income as the basis. Our tax calculators start from taxable income (after deductions). We do not reproduce the deduction rules that differ by canton — they would be needed for an exact comparison at the gross-income level.
• Capitals as the reference. For cantonal taxes we use the multiplier of the cantonal capital. Your municipality of residence can be cheaper or more expensive; the canton pages show the range.
• Excluding church and personal tax. Denominational taxes and fixed personal taxes are not included.
• Income only. Wealth tax is not part of the current calculators.
• Employer-dependent social deductions. NBU and BVG contributions vary by employer and pension fund; we calculate with the statutory minimum.

All calculations are for guidance only. Binding is the official assessment by the competent tax authority. All data sources are listed under Sources.