Build for a gap

Step 2 of 4 · ProjectsBy kind

All projects By kind Calculators

Calculators: 81 open source projects.

Small tools that compute one tax for one country.

81 projects62 maintained15 on the map32 jurisdictions + globalFacts checked 6 Oct 2026

Browse these by tax area

Income tax Corporate tax Benefits Payroll tax VAT & indirect Cross-cutting

bdtariffPython package for Bangladesh customs tariff lookup and import duty calculation, on PyPI as bdtariff.CalculatorBD

beancount-plugin-tax-ukBeancount plugin that computes UK capital gains with Section 104 pooling and exports Excel reports.CalculatorUKFor individual taxpayers

before-you-payStatic decision tool for Irish outbound withholding tax: which rule decides and at what rate.CalculatorIELicence unknown

beps2-pillar-twoTypeScript app projecting Pillar Two top-up tax for Hong Kong, Singapore and Japan groups under their regimes.CalculatorHK · SG · JPLicence unknown

BittyTaxCommand-line tools that turn wallet and exchange records into UK cryptoasset tax reports.CalculatorUKFor individual taxpayers

canada-hsa-calculatorTypeScript library and CLI for Canadian small-business health spending account tax savings, 2025 brackets.CalculatorCAFor individual taxpayers

Capital Gains CalculatorPython tool for UK capital gains tax on broker transaction histories using HMRC matching rules.CalculatorUKFor individual taxpayers

cgt-toolCommand-line tool for UK Capital Gains Tax on share sales that applies HMRC matching rules offline.CalculatorUKFor individual taxpayers

clt-vs-pjCompares Brazilian CLT employment with PJ contracting for tech workers: INSS, IRRF, Simples Nacional, ISS.CalculatorBRFor individual taxpayersLicence unknown

CoinTaxmanPython tool that calculates German crypto tax from exchange account statements.CalculatorDEFor individual taxpayers

CoolTaxToolUK tax calculator with charts for take-home pay, salary sacrifice and pension contributions.CalculatorUKFor individual taxpayers

corp-finance-coreRust finance library with a transfer pricing feature: tested party versus comparables, range, price by method.CalculatorGlobal

crypto-tax-calculatorImports crypto transactions from exchanges and wallets and produces tax reports.CalculatorGlobalFor individual taxpayers

Dutch Tax Income CalculatorAngular web calculator for Dutch income tax; the rules sit in a separate npm package.CalculatorNLFor individual taxpayers

F24EP Ravvedimento Operoso 2.0TypeScript app that computes the Italian ravvedimento operoso (late-payment penalty and interest) for F24EP.CalculatorITFor individual taxpayersLicence unknown

Grenzgaenger-RechnerReact calculator for cross-border workers between St. Gallen and Austria: source tax and social insurance.CalculatorAT · CHFor individual taxpayers

import_tax_calculatorDjango web calculator of Ukrainian import taxes on parcels.CalculatorUAFor individual taxpayers

income-tax-calculatorCommand-line script that converts share transaction reports into Lithuanian VMI tax declaration figures.CalculatorLTFor individual taxpayers

Income-Tax-Interest-Calculator (aisumitb)Browser calculator for Indian income tax interest under sections 234A, 234B and 234C.CalculatorINFor individual taxpayersLicence unknown

indonesia-tax-calculatorIndonesian tax calculator for foreign investors, with withholding tax and treaty rates for 14 countries.CalculatorID

Inflop.VatSharp.NET library for EU VAT calculation under Directive 2006/112/EC with three calculation methods.CalculatorEU

interactive-brokers-veroilmoitusFIFO capital gains calculator for Finnish Interactive Brokers users that runs with Docker.CalculatorFIFor individual taxpayers

IRS EITC AssistantThe IRS Earned Income Tax Credit Assistant questionnaire, built on Fact Graph and Form Builder.CalculatorUS

IRS Tax Withholding EstimatorThe IRS Tax Withholding Estimator, built on Fact Graph and Form Builder.CalculatorUS

nepal-hs-code-finderNepal Customs Tariff 2026/27 search with a duty calculator, an AI assistant and trade statistics.CalculatorNPLicence unknown

nepal-knitwear-sourcing-toolsRules-of-origin checker, Nepal-to-India duty calculator and duty dataset for knitwear importers.CalculatorNP · IN

opentaxationMalaysian calculator comparing tax for a sole proprietorship against a private company (Sdn Bhd).CalculatorMYFor individual taxpayers

pillar-two-toolLocal GloBE calculator: ETR, substance carve-out and top-up tax per jurisdiction, QDMTT/IIR/UTPR, GIR export.CalculatorGlobal

py1040Python program that computes US federal Form 1040 income tax from an interview and an input form.CalculatorUSFor individual taxpayers

ratioNuxt 4 calculator for Polish B2B contractors comparing tax forms, ZUS contributions and IP Box.CalculatorPLFor individual taxpayers

retirement_income_tax_planner_CanadaBrowser planner for Canadian retirement income: RRIF, TFSA, CPP, OAS, tax and investment scenarios.CalculatorCAFor individual taxpayersPolyForm Noncommercial 1.0.0

RP2Privacy-focused crypto tax calculator with country plugins and FIFO LIFO and HIFO accounting.CalculatorUS · JP · ES · IEFor individual taxpayers

salarySalary calculator website for the Basque Country, estimating net pay with IRPF.CalculatorESFor individual taxpayers

swisstaxcalculatorSwiss income, wealth and pension-withdrawal tax for all cantons, as a Nuxt app with a REST API.CalculatorCHFor individual taxpayers

Tax-Calculator (jdspr)React calculator for Belgian self-employed: INASTI contributions, income tax (IPP), VAT and expenses.CalculatorBEFor individual taxpayersLicence unknown

tax-extension-payment-calculatorClient-side calculator for 2025 US federal and California extension payments, with penalties and interest.CalculatorUSFor individual taxpayersLicence unknown

tax-helper (hinosxz)Next.js app for French and US citizens filing taxes on income from company equity (RSUs, ISOs, ESPP).CalculatorFR · USFor individual taxpayersLicence unknown

tax-penalty-calculator (Sivkov77)Python calculator for Russian tax late-payment penalties (peni).CalculatorRUFor individual taxpayersLicence unknown

tax-provision (Ritesh123423)Browser workpaper for a tax provision: current and deferred tax, movements, journals, ETR reconciliation.CalculatorGlobalLicence unknown

taxcalculatorghVue web calculator for Ghana's progressive income tax that shows take-home pay.CalculatorGHFor individual taxpayersLicence unknown

TaxGyaanIndian tax calculators, a GST invoice generator and EMI and SIP tools, as a React web app.CalculatorINFor individual taxpayersLicence unknown

Taxing212Browser-based UK capital gains calculator for Trading 212 CSV exports with Section 104 pooling.CalculatorUKFor individual taxpayers

TaxlyCompares India's old and new income tax regimes and finds unused deductions for salaried people, FY 2025-26.CalculatorINFor individual taxpayersLicence unknown

TaxProvision (Singapore)Static single-page Singapore corporate tax provision workpaper, from accounting profit to chargeable income.CalculatorSGLicence unknown

timahiSplits capital gains and dividends into India's five Schedule CG periods, with totals for each period.CalculatorINFor individual taxpayersLicence unknown

Transizione 5.0 CalculatorLibrary that calculates the Transizione 5.0 super-depreciation benefit for Italian SME AI investments.CalculatorIT

tw-tax-calculator-exReact calculator for Taiwan individual income tax, with three filing methods for married couples.CalculatorTWFor individual taxpayers

tw-tax-penalty-calcTaiwan tax late-payment surcharge and interest calculator.CalculatorTWFor individual taxpayersLicence unknown

UK Investment Tax CalculatorBrowser-based UK capital gains and dividend tax calculator for Interactive Brokers exports.CalculatorUKFor individual taxpayers

vat-penalty-calc (Korea)Korean VAT penalty tax (gasanse) calculator.CalculatorKRFor individual taxpayersLicence unknown

Withholding-Tax-Rates-2026Single-file static calculator of Bangladesh withholding tax rates for 2026; README in Bengali.CalculatorBDLicence unknown

ADVANCE-TAX-INTEREST-CALCULATORJavaScript calculator for interest payable on Indian advance tax shortfalls.CalculatorINInactive since 2025For individual taxpayersLicence unknown

asc740-tax-provisionSix-sheet linked Excel model of a corporate income tax provision under ASC 740 for a hypothetical company.CalculatorUSDemoLicence unknown

bd-income-tax-calculatorVue 3 web calculator for Bangladesh income tax with investment rebates and a PDF report.CalculatorBDInactive since 2025For individual taxpayersLicence unknown

bd-tax-calculatorVue 3 calculator for Bangladesh individual income tax with investment-based rebates, run in the browser.CalculatorBDInactive since 2025For individual taxpayers

BitcoinTaxerWeb app that calculates capital gains and losses on Bitcoin trades.CalculatorGlobalInactive since 2025For individual taxpayers

cbcr-safe-harbour-monitorMVP that runs the three transitional CbCR safe harbour tests per jurisdiction and year as a risk warning.CalculatorGlobalDemoNeeds a paid serviceLicence unknown

cptpp-projectOCaml CPTPP rules of origin and tariff calculator, written as an educational project.CalculatorGlobalDemo

crypto-taxNext.js calculator for crypto tax on Japan's miscellaneous income from a personal learning project.CalculatorJPInactive since 2022DemoFor individual taxpayers

Customs-CalculatorBrowser app with an Express API estimating Philippine import costs: HS search, duty and VAT; unfinished.CalculatorPHDemo

deep-agentic-supply-chain-ai (Hugging Face Space)Gradio demo that rates an intercompany transaction's risk from the gap between tested and benchmark margins.CalculatorGlobalDemo

DeFi TaxesImports DeFi transactions from many blockchains and calculates the tax; needs paid third-party data APIs.CalculatorGlobalInactive since 2025Needs a paid serviceFor individual taxpayersLicence unknown

german-income-tax-calculatorBrowser calculator for German net income: income tax, solidarity surcharge, church tax, social contributions.CalculatorDEInactive since 2025For individual taxpayers

Impot-CalculateurGo web app computing Tunisian withholding (RAS) by supplier type and VAT for finance professionals.CalculatorTNDemoLicence unknown

income_tax_calculatorR Shiny app that calculates salary income tax in Nepal for fiscal years 2078/79 and 2079/80.CalculatorNPInactive since 2022For individual taxpayersLicence unknown

incometax_calculatorPHP web page that computes Indian income tax.CalculatorINInactive since 2022For individual taxpayersLicence unknown

Labour Income Tax CalculatorAngular calculator showing how income tax would change under proposed Labour party policies.CalculatorUKInactive since 2019For individual taxpayers

lohnsteuerTypeScript library to calculate German wage tax and solidarity surcharge for 2014 to 2019.CalculatorDEInactive since 2019

motorrijtuigenbelastingTypeScript SDK and CLI that calculate Dutch motor vehicle tax from vehicle data and RDW lookups.CalculatorNLInactive since 2024For individual taxpayers

my-next-filingBrowser app for Indian freelancers: income tax estimate under presumptive rules and a dated filing plan.CalculatorINDemoFor individual taxpayers

permanent-establishment-hubStatic study tool with six permanent establishment calculators across 16 treaties, MLI articles included.CalculatorGlobalDemo

Pillar Two GloBE ETR calculatorPython scripts computing jurisdictional ETR, top-up tax, the UTPR allocation and deferred tax recapture.CalculatorGlobalDemoLicence unknown

Project House Calc WebBrowser calculator for income from house property under Indian income tax law, ported from an Android app.CalculatorINInactive since 2020For individual taxpayers

SmartTaxWeb calculator for Nepal personal income tax, using the 2080/81 budget rules.CalculatorNPInactive since 2024For individual taxpayers

tax_compareFlask website for comparing income tax in different regions; the README names no region or year.CalculatorUK · DEInactive since 2022For individual taxpayers

tax-interest-calculator (nieinter)Simple Python calculator for interest on late Polish tax payments.CalculatorPLInactive since 2025For individual taxpayersLicence unknown

Tax-Provision-Day-17-of-30UK corporation tax provision estimator: book-to-tax, marginal relief, IAS 12 and FRS 102 deferred tax.CalculatorUKDemo

tax-toolPython script that works out cost basis for VMware shares after the Broadcom merger from E*TRADE exports.CalculatorUSInactive since 2025For individual taxpayersNon-commercial use only

Transfer_Pricing (loan spreads)XGBoost model estimating arm's length intercompany loan spreads from synthetic bond data, with a Streamlit UI.CalculatorGlobalDemoLicence unknown

Transfer-Pricing-Risk-AssessmentAndroid app that scores a company's transfer pricing risk from a questionnaire based on the OECD Guidelines.CalculatorGlobalArchivedLicence unknown

UK Trade Tariff duty calculatorThe Online Trade Tariff's Rails duty calculator, archived in June 2025.CalculatorUKArchived

Labels mark what to check before you rely on an entry: inactive or archived code, demos, paid services and unclear licences. Only maintained projects for companies and tax authorities appear on the map. Search and filter the whole list.

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Next · Step 3 of 4The gapsThe activities with no open project yet, and the partly covered ones, with what to build on.