rel.tax — Multi-Country B2B Tax Calculator API

Free, open-source API for calculating self-employed and contractor taxes across 50 countries. Built for AI agents.

Browse Countries

Base URL: https://rel.tax

Endpoints

GET/v1/calculate/:country?paramsCalculate taxes (query params)

POST/v1/calculate/:countryCalculate taxes (JSON body)

GET/v1/countriesList supported countries

GET/v1/countries/:countryCountry-specific docs

GET/openapi.jsonOpenAPI 3.1 specification

GET/.well-known/ai-plugin.jsonAI plugin manifest

GET/healthHealth check

Quick Example

curl "https://rel.tax/v1/calculate/de?income=60000"

POST Example

curl -X POST https://rel.tax/v1/calculate/us \
  -H "Content-Type: application/json" \
  -d '{"income": 100000, "qbiDeduction": true}'

All endpoints return JSON. CORS enabled for all origins. No authentication required.

Supported Countries

50 countries live. Click any card to see full parameter docs below.

🇵🇱

Poland

ZUS, Health, PIT

🇩🇪

Germany

ESt, Soli, Church, Social

🇳🇱

Netherlands

Box 1, ZVW, MKB

🇬🇧

United Kingdom

Income Tax, NIC

🇪🇸

Spain

IRPF, RETA

🇵🇹

Portugal

IRS, SS, Simplified

🇪🇪

Estonia

FIE, Social Tax

🇷🇸

Serbia

Preduzetnik, Pausalac

🇺🇸

United States

SE Tax, Federal ISR

🇨🇦

Canada

CPP, EI, Provincial

🇲🇽

Mexico

RESICO, ISR

🇦🇺

Australia

Income Tax, Medicare

🇳🇿

New Zealand

PAYE, ACC, KiwiSaver

🇯🇵

Japan

Income, Resident, NHI

🇬🇪

Georgia

SBS 1% Turnover

🇦🇲

Armenia

IT 1%, Turnover Tax

🇧🇬

Bulgaria

10% flat, 25% NPR

🇨🇿

Czech Republic

OSVČ, 15%/23%, Paušál

🇷🇴

Romania

PFA, SRL 1% micro

🇦🇪

UAE

0% PIT, 9% corp

🇲🇪

Montenegro

Progressive 0/9/15%

🇨🇾

Cyprus

Progressive, GESY

🇸🇬

Singapore

Progressive, MediSave

🇭🇷

Croatia

Obrt, Paušalni

🇭🇺

Hungary

KATA, EV

🇹🇭

Thailand

Progressive brackets

🇲🇾

Malaysia

Progressive, Personal relief

🇨🇷

Costa Rica

Territorial tax, CCSS

🇮🇩

Indonesia

UMKM 0.5%, Progressive

🇨🇴

Colombia

UVT progressive, IBC

🇧🇪

Belgium

Progressive, Tiered social

🇫🇷

France

Micro-BNC, VL

🇵🇭

Philippines

8% flat, Graduated

🇮🇹

Italy

Forfettario, IRPEF

🇱🇹

Lithuania

Progressive, Sodra

🇬🇷

Greece

Progressive, EFKA

🇮🇪

Ireland

Income Tax, USC, PRSI

🇦🇹

Austria

Progressive, SVS

🇸🇪

Sweden

Egenavgifter, Municipal

🇮🇱

Israel

Progressive, NI, Health

🇮🇳

India

44ADA, New/Old Regime

🇩🇰

Denmark

AM-bidrag, Bundskat

🇫🇮

Finland

YEL, Progressive

🇳🇴

Norway

Trinnskatt, Trygdeavgift

🇨🇭

Switzerland

Federal, Cantonal, AHV

🇱🇻

Latvia

PIT progressive, Micro

🇸🇰

Slovakia

SZČO, 15% flat, Paušál

🇸🇮

Slovenia

Normiranec, Progressive

🇲🇹

Malta

Progressive, Class 2 SSC

🇹🇷

Turkey

BAĞ-KUR, Progressive

🌍

Try the API interactively

WhereTo.Work lets you compare take-home pay across countries side by side — powered by this API. Free, no signup required.

Open WhereTo.Work

🇵🇱 Poland

Tax Year 2026 · Polish B2B: ZUS, Health Insurance, PIT

Example

GET /v1/calculate/pl?income=10000&taxationType=lumpsum&lumpSumRate=12

Parameters

Parameter	Type	Default	Description
`income`	number	required	Monthly gross income PLN
`taxationType`	string	`lumpsum`	`lumpsum`, `linear`, `scale`
`lumpSumRate`	number	`12`	One of: 2, 3, 5.5, 8.5, 10, 12, 14, 15, 17
`zusRate`	string	`normal`	`normal`, `preferential`, `start`, `none`
`sickInsurance`	boolean	`false`	Include chorobowe (2.45%)
`costs`	number	`0`	Monthly business costs PLN
`paidDaysOff`	number	`26`	Vacation days/year
`weeklyHours`	number	`40`	Weekly working hours
`zusBase`	number	`60`	ZUS base as % of avg salary
`sickDays`	number	`0`	Days on sick leave
`vatPayer`	boolean	`true`	Include VAT calculation (23%)

🇳🇿 New Zealand

Tax Year 2026 (Apr 2025 - Mar 2026) · PAYE, ACC, KiwiSaver

Example

GET /v1/calculate/nz?income=75000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Gross income NZD
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`kiwiSaverRate`	number	`3`	One of: 0, 3, 4, 6, 8, 10
`studentLoan`	boolean	`false`	Has student loan
`acc`	boolean	`true`	Include ACC earners' levy (1.67%)
`gstRegistered`	boolean	`false`	GST registered (15%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇦🇺 Australia

Tax Year 2026 (Jul 2025 - Jun 2026) · Income Tax, Medicare, HELP/HECS

Example

GET /v1/calculate/au?income=100000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Taxable income AUD
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`helpDebt`	boolean	`false`	Has HELP/HECS student loan
`medicareLevyExempt`	boolean	`false`	Full Medicare levy exemption
`privateHealth`	boolean	`false`	Has private hospital cover
`superRate`	number	`0`	Self-funded super % (0 = employer default 12%)
`gstRegistered`	boolean	`false`	GST registered (10%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇬🇧 United Kingdom

Tax Year 2026 (Apr 2025 - Apr 2026) · Income Tax, Class 4 NIC, Student Loans

Example

GET /v1/calculate/gb?income=50000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income GBP
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`region`	string	`england`	`england` or `scotland`
`studentLoan`	string	`none`	`none`, `plan1`, `plan2`, `plan4`, `plan5`, `postgrad`
`vatRegistered`	boolean	`false`	VAT registered (20%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`28`	Annual leave days

🇺🇸 United States

Tax Year 2025 · Federal Self-Employment Tax & Income Tax (Single Filer)

Example

GET /v1/calculate/us?income=100000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Net self-employment income USD
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`filingStatus`	string	`single`	`single`
`qbiDeduction`	boolean	`true`	Apply QBI deduction (20%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇨🇦 Canada

Tax Year 2025 · Federal + Provincial: CPP, EI, Income Tax

Example

GET /v1/calculate/ca?income=100000&province=ON

Parameters

Parameter	Type	Default	Description
`income`	number	required	Net self-employment income CAD
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`province`	string	`ON`	ON, BC, AB, QC, MB, SK, NS, NB, PE, NL, YT, NT, NU
`eiOptIn`	boolean	`false`	Opted into EI (maternity/compassionate only)
`gstRegistered`	boolean	`false`	GST/HST registered
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇩🇪 Germany

Tax Year 2025 · Einkommensteuer, Solidarity Surcharge, Church Tax, Social Insurance

Example

GET /v1/calculate/de?income=60000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`churchTax`	string	`none`	`none`, `8` (BW/BY), `9` (other states)
`hasChildren`	boolean	`true`	Affects Pflegeversicherung rate
`healthInsurance`	string	`statutory`	`statutory` or `none`
`zusatzbeitrag`	number	`2.5`	GKV supplementary rate %
`pensionInsurance`	boolean	`false`	Voluntary pension insurance
`gewerbesteuer`	boolean	`false`	Subject to trade tax (Gewerbetreibende)
`hebesatz`	number	`400`	Municipal trade tax multiplier %
`vatRegistered`	boolean	`false`	VAT registered (19%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`30`	Annual leave days

🇪🇸 Spain

Tax Year 2025 · IRPF (Income Tax), Autonomo Social Security (RETA)

Example

GET /v1/calculate/es?income=40000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Annual deductible business expenses EUR
`newAutonomo`	boolean	`false`	New autonomo (tarifa plana SS + 20% IRPF reduction)
`vatRegistered`	boolean	`false`	IVA registered (21%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`22`	Annual leave days

🇪🇪 Estonia

Tax Year 2026 · FIE (Sole Proprietor): Income Tax, Social Tax, II Pillar Pension

Example

GET /v1/calculate/ee?income=60000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Gross business income EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`pensionPillarRate`	number	`2`	II pillar: `0`, `2`, `4`, or `6`%
`vatRegistered`	boolean	`false`	VAT registered (22%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇯🇵 Japan

Tax Year 2025 · Income Tax, Resident Tax, Business Tax, NHI, National Pension

Example

GET /v1/calculate/jp?income=5000000
GET /v1/calculate/jp?income=10000000&blueReturn=none&businessTaxRate=3

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross business income JPY
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Annual deductible business expenses JPY
`blueReturn`	string	`full`	Blue return tier: `full` (650k), `paper` (550k), `basic` (100k), `none`
`businessTaxRate`	number	`5`	Business tax rate: `3`, `4`, or `5`%
`nhiRate`	number	`10`	NHI income-based rate % (varies by municipality)
`consumptionTax`	boolean	`false`	Consumption tax registered (10%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`15`	Annual leave days

🇷🇸 Serbia

Tax Year 2025 · Preduzetnik (licna zarada) & Pausalac (lump-sum)

Example

GET /v1/calculate/rs?income=60000
GET /v1/calculate/rs?income=50000&taxModel=pausalac&pausalnaOsnovica=50000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`currency`	string	`EUR`	`EUR` or `RSD` (input/output currency)
`expenses`	number	`0`	Annual deductible expenses (preduzetnik only)
`taxModel`	string	`preduzetnik`	`preduzetnik` or `pausalac`
`pausalnaOsnovica`	number	`0`	Monthly lump-sum base in RSD (required for pausalac)
`vatRegistered`	boolean	`false`	PDV registered (20%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇬🇪 Georgia

Tax Year 2025 · Small Business Status (SBS) Turnover Tax, Pension

Example

GET /v1/calculate/ge?income=100000
GET /v1/calculate/ge?income=100000&taxRegime=regular&expenses=20000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Gross business income GEL
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`taxRegime`	string	`sbs`	`sbs` (1% turnover) or `regular` (20% flat)
`expenses`	number	`0`	Business expenses GEL (regular regime only)
`vatRegistered`	boolean	`false`	VAT registered (18%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇦🇲 Armenia

Tax Year 2025 · IT Turnover Tax (1%), General Turnover (10%), Social Payments

Example

GET /v1/calculate/am?income=50000000&taxRegime=turnover_it
GET /v1/calculate/am?income=20000000&taxRegime=turnover_it

Parameters

Parameter	Type	Default	Description
`income`	number	required	Gross business income AMD
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`currency`	string	`AMD`	`AMD` or `USD` (label only)
`taxRegime`	string	`turnover_it`	`turnover_it` (1%), `turnover_general` (10%), `regular` (20%)
`expenses`	number	`0`	Business expenses AMD (regular regime only)
`vatRegistered`	boolean	`false`	VAT registered (20%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇲🇽 Mexico

Tax Year 2025 · RESICO (Simplified Trust) & General ISR

Example

GET /v1/calculate/mx?income=1000000
GET /v1/calculate/mx?income=500000&taxRegime=general&expenses=100000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Gross business income MXN
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`taxRegime`	string	`resico`	`resico` (1-2.5% tiered) or `general` (ISR progressive)
`expenses`	number	`0`	Business expenses MXN (general regime only)
`imssOptIn`	boolean	`false`	Voluntary IMSS social security
`vatRegistered`	boolean	`true`	IVA registered (16%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`15`	Annual leave days

🇵🇹 Portugal

Tax Year 2025 · IRS (Income Tax), Social Security, Simplified Regime

Example

GET /v1/calculate/pt?income=60000
GET /v1/calculate/pt?income=60000&accountingRegime=organized&expenses=15000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`activityType`	string	`services_listed`	`services_listed`, `services_other`, `sales`
`expenses`	number	`0`	Business expenses EUR (organized regime only)
`accountingRegime`	string	`simplified`	`simplified` or `organized`
`newFreelancer`	boolean	`false`	First 12 months (social security exempt)
`vatRegistered`	boolean	`false`	IVA registered (23%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`22`	Annual leave days

🇧🇬 Bulgaria

Tax Year 2025 · Freelancer (свободна професия) & Sole Trader (ЕТ): Social, Health, Income Tax

Example

GET /v1/calculate/bg?income=60000
GET /v1/calculate/bg?income=60000&activityType=sole_trader&expenses=20000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Gross business income BGN
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`activityType`	string	`freelancer`	`freelancer` (10%, 25% NPR) or `sole_trader` (15%, actual expenses)
`expenses`	number	`0`	Business expenses BGN (sole_trader only)
`includeOzm`	boolean	`false`	Include illness & maternity (3.5%)
`vatRegistered`	boolean	`false`	VAT registered (20%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇨🇿 Czech Republic

Tax Year 2025 · OSVČ: Income Tax (15%/23%), Social Insurance (29.2%), Health Insurance (13.5%), Flat-Rate Expenses

Example

GET /v1/calculate/cz?income=1000000
GET /v1/calculate/cz?income=1000000&expenseMethod=flat_80
GET /v1/calculate/cz?income=1000000&expenseMethod=actual&expenses=300000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Gross business income CZK
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenseMethod`	string	`flat_60`	`flat_80` craft, `flat_60` trades (default), `flat_40` professionals, `flat_30` rental, `actual`
`expenses`	number	`0`	Actual business expenses CZK (expenseMethod=actual only)
`vatRegistered`	boolean	`false`	DPH registered (21%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`25`	Annual leave days

🇷🇴 Romania

Tax Year 2025 · PFA (Freelancer) & SRL Micro-Enterprise (1%/3% Turnover Tax)

Example

GET /v1/calculate/ro?income=120000&expenses=20000
GET /v1/calculate/ro?income=120000&entityType=srl_micro

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross revenue RON
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`entityType`	string	`pfa`	`pfa` (freelancer) or `srl_micro` (micro-enterprise)
`expenses`	number	`0`	Annual business expenses RON (PFA only)
`microRate`	number	`1`	Micro tax %: `1` (with employee) or `3` (without)
`optInCas`	boolean	`false`	Opt into CAS pension when below threshold (PFA only)
`vatRegistered`	boolean	`false`	TVA registered (19%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`21`	Annual leave days

🇦🇪 United Arab Emirates

Tax Year 2025 · 0% Personal Income Tax / 9% Corporate Tax (Free Zone)

Example

GET /v1/calculate/ae?income=500000&entityType=freezone&expenses=50000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross revenue AED
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`entityType`	string	`freelancer`	`freelancer` (0% PIT) or `freezone` (9% corp tax)
`expenses`	number	`0`	Business expenses AED (freezone only)
`vatRegistered`	boolean	`false`	VAT registered (5%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`30`	Annual leave days

🇲🇪 Montenegro

Tax Year 2025 · Progressive Income Tax (0/9/15%) + Social Contributions (26%)

Example

GET /v1/calculate/me?income=60000&expenses=5000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross revenue EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Annual business expenses EUR
`vatRegistered`	boolean	`false`	PDV registered (21%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇨🇾 Cyprus

Tax Year 2025 · Progressive Income Tax (0–35%) + Social Insurance (16.6%) + GESY (2.65%)

Example

GET /v1/calculate/cy?income=80000&expenses=5000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross revenue EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Annual business expenses EUR
`vatRegistered`	boolean	`false`	FPA registered (19%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇸🇬 Singapore

Tax Year 2025 · Progressive Income Tax (0–24%) + MediSave (8–10.5%)

Example

GET /v1/calculate/sg?income=120000&expenses=10000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross revenue SGD
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Deductible business expenses SGD
`ageGroup`	string	`below35`	`below35`, `age35to44`, `age45to49`, `age50plus`
`vatRegistered`	boolean	`false`	GST registered (9%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`14`	Annual leave days

🇭🇷 Croatia

Tax Year 2025 · Obrt (20/30% + Surtax) & Paušalni Obrt (Fixed €230/mo)

Example

GET /v1/calculate/hr?income=60000&expenses=10000&taxModel=obrt
GET /v1/calculate/hr?income=35000&taxModel=pausalni

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross revenue EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`taxModel`	string	`obrt`	`obrt` (real income) or `pausalni` (flat-rate)
`expenses`	number	`0`	Business expenses EUR (obrt only)
`surtax`	string	`zagreb`	`zagreb` (18%), `split` (10%), `rijeka`/`osijek` (13%), `none`
`vatRegistered`	boolean	`false`	PDV registered (25%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇭🇺 Hungary

Tax Year 2025 · KATA (HUF 50k/mo flat tax) & EV (15% SZJA + 31.5% social)

Example

GET /v1/calculate/hu?income=12000000&taxModel=kata
GET /v1/calculate/hu?income=12000000&taxModel=ev&expenses=2000000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross revenue HUF
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`taxModel`	string	`kata`	`kata` (flat tax) or `ev` (individual entrepreneur)
`expenses`	number	`0`	Business expenses HUF (EV only)
`vatRegistered`	boolean	`false`	ÁFA registered (27%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇳🇱 Netherlands

Tax Year 2026 · Box 1 Income Tax, ZVW, Zelfstandigenaftrek, MKB-winstvrijstelling

Example

GET /v1/calculate/nl?income=60000
GET /v1/calculate/nl?income=60000&starter=true

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual business profit EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`starter`	boolean	`false`	First 3 years (startersaftrek €2,123)
`hoursExempt`	boolean	`false`	Does NOT meet 1,225-hour criterion
`vatRegistered`	boolean	`true`	BTW registered (21%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`25`	Annual leave days

🇹🇭 Thailand

Tax Year 2025 · Progressive 0–35%, Expense deduction, Personal allowance

Example

GET /v1/calculate/th?income=1200000
GET /v1/calculate/th?income=100000&incomePeriod=monthly&vatRegistered=true

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income THB
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`vatRegistered`	boolean	`false`	VAT registered (7%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`6`	Annual leave days

🇲🇾 Malaysia

Tax Year 2025 · Progressive 0–30%, Personal relief RM 9,000

Example

GET /v1/calculate/my?income=120000
GET /v1/calculate/my?income=10000&incomePeriod=monthly

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income MYR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`vatRegistered`	boolean	`false`	SST registered (8%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`11`	Annual leave days

🇨🇷 Costa Rica

Tax Year 2025 · Territorial tax, Progressive 0–25%, CCSS 10%

Example

GET /v1/calculate/cr?income=24000000
GET /v1/calculate/cr?income=24000000&expenses=5000000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income CRC
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Deductible business expenses CRC
`vatRegistered`	boolean	`false`	IVA registered (13%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`15`	Annual leave days

🇮🇩 Indonesia

Tax Year 2025 · UMKM 0.5% final tax & Progressive 5–35%

Example

GET /v1/calculate/id?income=1000000000&taxModel=umkm
GET /v1/calculate/id?income=300000000&taxModel=progressive

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross revenue IDR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`taxModel`	string	`umkm`	`umkm` (0.5% final) or `progressive` (5–35%)
`vatRegistered`	boolean	`false`	PPN registered (12%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`12`	Annual leave days

🇨🇴 Colombia

Tax Year 2025 · UVT-based progressive, IBC social contributions

Example

GET /v1/calculate/co?income=100000000
GET /v1/calculate/co?income=100000000&expenses=20000000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income COP
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Deductible business expenses COP
`vatRegistered`	boolean	`false`	IVA registered (19%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`15`	Annual leave days

🇧🇪 Belgium

Tax Year 2025 · Progressive 25–50%, Tiered social, Tax-free credit

Example

GET /v1/calculate/be?income=80000
GET /v1/calculate/be?income=80000&expenses=15000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Deductible business expenses EUR
`vatRegistered`	boolean	`false`	BTW registered (21%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇫🇷 France

Tax Year 2025 · Micro-BNC (23.1% social + progressive) & Versement Libératoire (25.3% flat)

Example

GET /v1/calculate/fr?income=60000&taxModel=micro_bnc
GET /v1/calculate/fr?income=60000&taxModel=versement_liberatoire

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual turnover EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`taxModel`	string	`micro_bnc`	`micro_bnc` or `versement_liberatoire`
`vatRegistered`	boolean	`false`	TVA registered (20%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`25`	Annual leave days

🇵🇭 Philippines

Tax Year 2025 · 8% Flat Rate or Graduated Progressive Income Tax

Example

GET /v1/calculate/ph?income=1500000&taxModel=flat_8
GET /v1/calculate/ph?income=1500000&taxModel=graduated

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross receipts PHP
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`taxModel`	string	`flat_8`	`flat_8` (8% above 250K) or `graduated` (progressive + 3% percentage tax)
`vatRegistered`	boolean	`false`	VAT registered (12%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`5`	Annual leave days

🇮🇹 Italy

Tax Year 2025 · Forfettario (15%/5% substitute tax) or Ordinario (IRPEF progressive) + INPS 26.07%

Example

GET /v1/calculate/it?income=60000&taxModel=forfettario
GET /v1/calculate/it?income=60000&taxModel=ordinario

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`taxModel`	string	`forfettario`	`forfettario` or `ordinario`
`startup`	boolean	`false`	First 5 years startup rate (5%, forfettario only)
`profitabilityCoefficient`	number	`0.78`	Taxable income as % of gross (forfettario)
`vatRegistered`	boolean	`false`	IVA registered (22%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇱🇹 Lithuania

Tax Year 2025 · Individual Activity: 3-bracket progressive (5/15/20%) + Sodra 19.5% + PSD health

Example

GET /v1/calculate/lt?income=60000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Annual business expenses EUR
`vatRegistered`	boolean	`false`	PVM registered (21%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇬🇷 Greece

Tax Year 2025 · 5-bracket progressive (9-44%) + EFKA social + optional 50% relocator regime

Example

GET /v1/calculate/gr?income=60000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Annual business expenses EUR
`newBusiness`	boolean	`false`	First 5 years (reduced EFKA)
`specialRegime`	boolean	`false`	50% income exemption for relocators (7 years)
`vatRegistered`	boolean	`false`	FPA registered (24%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇮🇪 Ireland

Tax Year 2025 · Income Tax (20/40%) + USC (5-bracket) + PRSI Class S (4.1%) - Tax Credits

Example

GET /v1/calculate/ie?income=80000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Annual business expenses EUR
`vatRegistered`	boolean	`false`	VAT registered (23%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇦🇹 Austria

Tax Year 2025 · 7-bracket progressive (0-55%) + SVS social 26.83% + Gewinnfreibetrag 15%

Example

GET /v1/calculate/at?income=80000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Annual business expenses EUR
`vatRegistered`	boolean	`false`	USt registered (20%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`25`	Annual leave days

🇸🇪 Sweden

Tax Year 2025 · Egenavgifter 28.97% + municipal ~32% + state 20% above SEK 613,900

Example

GET /v1/calculate/se?income=600000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income SEK
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Annual business expenses SEK
`municipalRate`	number	`0.3237`	Municipal tax rate (varies by kommun)
`vatRegistered`	boolean	`false`	Moms registered (25%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`25`	Annual leave days

🇮🇱 Israel

Tax Year 2025 · 7-bracket progressive (10-50%) + National Insurance + Health Tax + Credit Points

Example

GET /v1/calculate/il?income=300000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income ILS
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Annual business expenses ILS
`vatRegistered`	boolean	`false`	Ma'am registered (18%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`12`	Annual leave days

🇮🇳 India

Tax Year 2025 · Presumptive 44ADA | New Regime (7-bracket) | Old Regime (4-bracket) + 4% Cess

Example

GET /v1/calculate/in?income=3000000&taxModel=presumptive
GET /v1/calculate/in?income=2000000&taxModel=new_regime

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross receipts INR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`taxModel`	string	`presumptive`	`presumptive` (44ADA), `new_regime`, or `old_regime`
`vatRegistered`	boolean	`false`	GST registered (18%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`15`	Annual leave days

🇩🇰 Denmark

Tax Year 2025 · AM-bidrag 8% + Bundskat + Municipal + Topskat

Example

GET /v1/calculate/dk?income=600000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income DKK
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`municipalRate`	number	`0.251`	Municipal tax rate (varies by kommune)
`churchTax`	boolean	`false`	Include church tax
`churchRate`	number	`0.007`	Church tax rate
`vatRegistered`	boolean	`false`	Moms registered (25%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`25`	Annual leave days

🇫🇮 Finland

Tax Year 2025 · State Progressive + Municipal + YEL Pension 24.10% + Health 2.10%

Example

GET /v1/calculate/fi?income=60000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Annual business expenses EUR
`municipalRate`	number	`0.0928`	Municipal tax rate
`vatRegistered`	boolean	`false`	ALV registered (25.5%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`25`	Annual leave days

🇳🇴 Norway

Tax Year 2025 · Ordinary 22% + Trinnskatt (6-tier) + Trygdeavgift 10.9%

Example

GET /v1/calculate/no?income=700000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income NOK
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Annual business expenses NOK
`vatRegistered`	boolean	`false`	MVA registered (25%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`25`	Annual leave days

🇨🇭 Switzerland

Tax Year 2025 · Federal Progressive + Cantonal + AHV/IV/EO 10%

Example

GET /v1/calculate/ch?income=120000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income CHF
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Annual business expenses CHF
`cantonalRate`	number	`0.12`	Cantonal+municipal rate (default: Zurich approx)
`vatRegistered`	boolean	`false`	MWST registered (8.1%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`25`	Annual leave days

🇱🇻 Latvia

Tax Year 2025 · Standard PIT (20/23/31%) + SSC 31.07% | Micro-enterprise 25%

Example

GET /v1/calculate/lv?income=40000
GET /v1/calculate/lv?income=30000&taxModel=micro

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`taxModel`	string	`standard`	`standard` (progressive) or `micro` (25% flat)
`expenses`	number	`0`	Business expenses EUR (standard only)
`vatRegistered`	boolean	`false`	PVN registered (21%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇸🇰 Slovakia

Tax Year 2025 · SZČO: 15% (revenue ≤ 100K) or 19/25% + Social 33.15% + Health 15%

Example

GET /v1/calculate/sk?income=60000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`useFlatExpenses`	boolean	`true`	60% flat expenses (max EUR 20,000)
`actualExpenses`	number	`0`	Actual expenses (when flat=false)
`vatRegistered`	boolean	`false`	DPH registered (23%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇸🇮 Slovenia

Tax Year 2025 · Normiranec (eff. 4%) or Progressive (16-50%) + Social 38.20%

Example

GET /v1/calculate/si?income=80000&taxModel=normiranec
GET /v1/calculate/si?income=60000&taxModel=standard

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`taxModel`	string	`normiranec`	`normiranec` (80% norm. expenses) or `standard`
`expenses`	number	`0`	Business expenses (standard only)
`vatRegistered`	boolean	`false`	DDV registered (22%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`20`	Annual leave days

🇲🇹 Malta

Tax Year 2025 · Progressive (0-35%) + Class 2 SSC 15% (capped)

Example

GET /v1/calculate/mt?income=50000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income EUR
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Annual business expenses EUR
`vatRegistered`	boolean	`false`	VAT registered (18%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`24`	Annual leave days

🇹🇷 Turkey

Tax Year 2025 · Non-employment Progressive (15-40%) + BAĞ-KUR 34.5%

Example

GET /v1/calculate/tr?income=500000

Parameters

Parameter	Type	Default	Description
`income`	number	required	Annual gross income TRY
`incomePeriod`	string	`yearly`	`monthly` or `yearly`
`expenses`	number	`0`	Annual business expenses TRY
`bagkurBase`	string	`minimum`	`minimum`, `actual`, or `maximum`
`vatRegistered`	boolean	`false`	KDV registered (20%)
`weeklyHours`	number	`40`	Weekly working hours
`paidDaysOff`	number	`14`	Annual leave days

Response Format

All /v1/calculate/:country endpoints return a consistent JSON structure with country-specific details.

Response Structure

{
  "country": "de",
  "taxYear": 2025,
  "input": { /* echoed input parameters */ },
  "monthly": {
    "gross": 5000.00,
    "vat": 0,
    "grossWithVat": 5000.00,
    "socialInsurance": 846.89,
    "healthInsurance": 0,
    "incomeTax": 671.83,
    "totalDeductions": 1518.72,
    "net": 3481.28
  },
  "yearly": {
    "gross": 60000.00,
    "socialInsurance": 10162.68,
    "healthInsurance": 0,
    "incomeTax": 8061.92,
    "totalDeductions": 18224.60,
    "net": 41775.40
  },
  "rates": {
    "effectiveTaxRate": 0.3037,
    "dailyRate": 189.03,
    "hourlyRate": 23.63,
    "workingDays": 221
  },
  "details": { /* country-specific calculation details */ }
}

Field Reference

Field	Description
`monthly.gross`	Monthly gross income in local currency
`monthly.vat`	VAT/GST amount (0 if not registered)
`monthly.socialInsurance`	Social/pension contributions per month
`monthly.healthInsurance`	Health insurance per month (some countries fold this into socialInsurance)
`monthly.incomeTax`	Income tax per month
`monthly.net`	Take-home pay per month
`yearly.*`	Same fields annualized
`rates.effectiveTaxRate`	Total deductions as fraction of gross (0-1)
`rates.dailyRate`	Net income per working day
`rates.hourlyRate`	Net income per hour (based on weeklyHours)
`rates.workingDays`	Working days minus paid days off
`details`	Country-specific breakdown (brackets, bases, intermediate values)

Error Response

{ "error": "income is required and must be a positive number" }

Errors return HTTP 400 with a descriptive message. Unsupported country codes return HTTP 404.

Agent Integration Guide

Instructions for AI agents that need to calculate taxes programmatically.

MCP Server (Claude Desktop / Claude Code)

Use rel.tax as a native tool in Claude Desktop or Claude Code via Model Context Protocol:

npx @reltax/mcp-server

Add to your Claude Desktop config (claude_desktop_config.json):

{
  "mcpServers": {
    "reltax": {
      "command": "npx",
      "args": ["@reltax/mcp-server"]
    }
  }
}

Three tools are available:

reltax_list_countries — List all 50 supported countries
reltax_get_country_info — Get tax parameters for a country
reltax_calculate_tax — Calculate B2B taxes with full breakdown

Auto-Import

Import the OpenAPI 3.1 spec into your framework of choice:

LangChain — OpenAPIToolkit.from_openapi_spec(url)
OpenAI function calling — import as tool definitions
Claude tool use — convert paths to tool schemas
ChatGPT Plugin — discovered via /.well-known/ai-plugin.json

Step 1: Determine the Country

Use the two-letter ISO country code. Call /v1/countries for the full list of 50 supported countries.

Step 2: Build the Request

Only income is required. All other parameters have sensible defaults. Use GET with query params for simplicity:

GET https://rel.tax/v1/calculate/de?income=75000&churchTax=9

Step 3: Parse the Response

The key fields you likely need:

yearly.net — annual take-home pay
monthly.net — monthly take-home pay
rates.effectiveTaxRate — total tax burden as decimal
rates.hourlyRate — effective hourly rate after all deductions
yearly.totalDeductions — total annual taxes and contributions

Tips

Income is always in the country's local currency unless the country supports currency selection (Serbia: EUR or RSD)
All countries support incomePeriod (monthly/yearly). Poland defaults to monthly; most others default to yearly
To compare countries, normalize to yearly income first
The details object contains intermediate calculation values useful for explaining results
Fetch /v1/countries/:code for machine-readable parameter docs at runtime

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