The goal of this repository is to implement all the logic used to calculate the swiss taxes and serve it in a super fast service to do any kind of calculations in any kind of environment.
- Clone the repository
- yarn install (installs all the dependencies)
- yarn dev (runs the dev server)
- Nuxt 3 application with server api and static demo page (https://github.com/nuxt/nuxt)
- ./pages/index.vue shows an example page for calculating taxes
- Live preview https://swisstaxcalculator.vercel.app/
- Inspired by https://swisstaxcalculator.estv.admin.ch/#/calculator
- ./server/api/ API routes for tax calculation and locations
- ./lib/taxes/ covers all the tax logic
- ./data/ includes all the raw and parsed data
- Income & wealth (fortune)
- (Pension) capital withdrawal
- Taxable income
- Net income
- Gross income
The speciality about the gross- and net-income types is the deductions that are made automatically based on the tax input and the possible deductions.
https://swisstaxcalculator.estv.admin.ch/#/taxdata
Some information is from https://finpension.ch/de/vergleich-kapitalbezugssteuer/ and the updated values are from the individual canton tax laws directly.
To run the service, there is no database required. All the data is either in the code files or imported from the raw data during dev / build time using the following command.
yarn importdata <year>[,<year>,...] [--download]
Raw data: ./data/raw/...
Parsed data: ./data/parsed/...
Use the --download flag to fetch raw data directly from the ESTV API and import it in one step:
yarn importdata 2026 --download
yarn importdata 2024,2025,2026 --download
To import from existing raw files (without downloading), just run:
yarn importdata 2026
To import more tax years manually, copy the raw files into ./data/raw/<year>/ and run the importdata script. The raw data can be retrieved by looking into the requests done by the browser (just save the results):
- tarifs.json: https://swisstaxcalculator.estv.admin.ch/#/taxdata/tax-scales (API_exportManyTaxScales)
- deductions.json: https://swisstaxcalculator.estv.admin.ch/#/taxdata/deductions (API_exportManyDeductions)
- factors.json: https://swisstaxcalculator.estv.admin.ch/#/taxdata/tax-rates (API_exportManySimpleRates)
The data is parsed into small chunks, mostly per canton to guarantee a fast loading time and minimal memory consumption. Once loaded, the data is held in memory until the service is stopped.
In an always on environment, the data will be in memory until redeployed. This ensures maximum execution speed.
For cloud functions, the data has to be reloaded once the function was removed and reloaded into memory.
The Nuxt server exposes three JSON endpoints. Base URL is the deployment root (e.g. https://swisstaxcalculator.vercel.app).
Request body (TaxInput):
| Field | Type | Required | Description |
|---|---|---|---|
calculationType |
'incomeAndWealth' | 'capital' |
yes | incomeAndWealth = yearly income + fortune tax. capital = one-off pension-capital withdrawal tax. |
year |
number |
yes | Tax year (e.g. 2025). Must match a directory under data/parsed/. |
cantonId |
number |
yes | ESTV canton ID. Resolve from /api/locations. |
locationId |
number |
yes | BFS ID of the municipality (BfsID from /api/locations). |
relationship |
's' | 'm' | 'rp' | 'c' |
yes | Single, married, registered partnership, cohabitation. m/rp require persons.length === 2; s/c require 1. |
children |
number |
yes | Number of dependent children (affects deductions and the tarif group). |
fortune |
number |
yes | Net fortune in CHF. For calculationType: 'capital' this field carries the capital amount. |
persons |
TaxInputPerson[] |
yes | 1 or 2 persons (see below). |
deductions |
TaxDeductionGeneralInput |
no | Shared household deductions (see below). |
includeProgression |
boolean |
no | When true, the response includes a per-bracket breakdown for charting the effective marginal-rate progression (see Progression below). |
TaxInputPerson:
| Field | Type | Required | Description |
|---|---|---|---|
age |
number |
yes | Age in years (affects some deductions). |
confession |
'christ' | 'roman' | 'protestant' | 'other' |
yes | Church tax is levied only for the first three; other means no church tax. |
incomeType |
'gross' | 'net' | 'taxable' |
yes | Which level of income income represents. gross triggers automatic AHV/IV/EO/ALV/NBU/PK deductions; net only the income deductions; taxable skips all automatic deductions. |
income |
number |
yes | Income in CHF at the level given by incomeType. |
pkDeduction |
number |
no | Employee pension-fund contribution (in CHF) to deduct from a gross income. |
deductions |
TaxDeductionPerPersonInput |
no | Per-person deductions (see below). |
TaxDeductionPerPersonInput — all CHF, all optional:
insurancePremiums, pillar3a, mealCosts, travelExpenses, otherProfessionalExpenses, professionalExpensesSideline, otherDeductions.
TaxDeductionGeneralInput — all CHF, all optional:
insurancePremiumsKids, childcareCosts, debtInterest, maintenanceCostsRealEstate, otherDeductions.
All monetary amounts are in CHF. taxesTotal is the sum of all line items above it.
Set "includeProgression": true to receive a bracket-wise breakdown of the effective marginal tax rates. Useful for rendering staircase / bar charts of the user's position in the tarif.
"progression": {
"overall": { /* ProgressionResult — Bund + canton + city + church combined */ },
"bund": { /* ProgressionResult — federal (Bund) income tax only */ },
"cantonIncome": { /* ProgressionResult — canton income tax × full Steuerfuss */ },
"cantonFortune": { /* ProgressionResult — canton fortune tax × full Steuerfuss */ }
}ProgressionResult:
| Field | Type | Description |
|---|---|---|
taxableIncome |
number |
The taxable base (income or fortune) this progression was evaluated on, in CHF. |
brackets |
ProgressionBracket[] |
All brackets from the tarif, lowest rate first. See below. |
currentBracketIndex |
number |
Index into brackets of the bracket that contains the user's taxableIncome. |
amountIntoCurrentBracket |
number |
How many CHF of the user's income are already in the current bracket (taxableIncome − currentBracket.lowerBound). |
amountToNextBracket |
number | null |
CHF of additional income needed to cross into the next bracket. null when already in the tarif's top bracket. |
nextBracketPercent |
number | null |
Effective marginal rate of the next bracket (null at top). |
previousBracketPercent |
number | null |
Effective marginal rate of the previous bracket (null at bottom). |
ProgressionBracket:
| Field | Type | Description |
|---|---|---|
lowerBound |
number |
CHF threshold where this bracket starts. |
upperBound |
number |
CHF threshold where this bracket ends. If upperBound === lowerBound the bracket is open-ended at the top ("ab CHF X"). |
percent |
number |
Effective marginal rate in percent (e.g. 16.92 means 16.92%). For cantonIncome / cantonFortune this already includes the canton + city + church multiplier; for overall it also stacks the federal rate. |
amountInBracket |
number |
CHF of the user's income that falls inside this bracket. 0 for brackets above the user's income. |
taxInBracket |
number |
CHF of tax generated in this bracket for the user. 0 for brackets above the user's income. |
Notes:
- The
overallprogression is projected onto the canton-taxable-income axis; Bund thresholds are shifted bytaxableIncomeCanton − taxableIncomeBundso both systems line up. - Canton
FREIBURGtarifs are continuous (no discrete steps) and return a single-bracket progression at the effective rate for the given income. - Minor rounding differences (a few CHF) can exist between
sum(brackets.taxInBracket)and the corresponding headline tax number because the underlying calculation rounds down to the nearest 100 CHF at intermediate steps.
curl -X POST https://swisstaxcalculator.vercel.app/api/taxes \
-H 'Content-Type: application/json' \
-d '{
"calculationType": "incomeAndWealth",
"year": 2025,
"cantonId": 26,
"locationId": 1,
"relationship": "s",
"children": 0,
"fortune": 0,
"persons": [{
"age": 35,
"confession": "other",
"incomeType": "gross",
"income": 100000
}],
"includeProgression": true
}'500 responses include the usual Nitro error envelope ({ statusCode, statusMessage, message, ... }). Common causes:
- Unknown
cantonId/locationId/yearcombination (no factors or tarifs on disk). - Invalid person count for the given
relationship(seevalidateTaxInput).
Returns the list of Swiss municipalities for the default tax year, one entry per BFS ID:
[{ "TaxLocationID": 891400000, "BfsID": 1, "BfsName": "Aeugst am Albis", "CantonID": 26, "Canton": "ZH" }, ...]Use BfsID as locationId and CantonID as cantonId in a POST /api/taxes call.
Returns the static dropdown metadata the reference UI uses: available years, relationships, confessions, income types, and deduction field configs with default values and localized (German) labels. Handy if you want to build your own form without hard-coding these enums.
For issues and questions, please create an issue.
Please contact me (michael.bolliger@gmail.com) if you want to contribute or use this repository in your own environment or application. Thank you.
{ "input": { /* echo of TaxInput */ }, "taxesIncomeCanton": 0, "taxesIncomeCity": 0, "taxesIncomeChurch": 0, "taxesFortuneCanton": 0, "taxesFortuneCity": 0, "taxesFortuneChurch": 0, "taxesIncomeBund": 0, "taxesPersonnel": 0, "taxesTotal": 0, "details": { "grossNetDetails": [{ "person": { /* ... */ }, "grossIncome": 0, "ahvIvEo": 0, "alv": 0, "nbu": 0, "pk": 0, "netIncome": 0 }], "netIncomeCanton": 0, "netIncomeBund": 0, "deductionsIncome": [{ "id": "pillar3a", "name": "…", "target": "P1", "amountCanton": 0, "amountBund": 0 }], "deductionsFortune": [], "taxableFortuneCanton": 0, "taxableIncomeCanton": 0, "taxableIncomeBund": 0 }, "progression": { /* only when includeProgression === true, see below */ } }