TaxLab — NZ Income Tax Calculator

Calculates NZ income tax, ACC levy, and KiwiSaver contributions from an annual salary.

Running with Docker

Single container — the .NET API serves the React frontend from wwwroot/.

docker-compose up --build

• App + API: http://localhost:3000
• Swagger UI: http://localhost:3000/swagger

TypeScript type generation

Frontend types are generated from the OpenAPI spec at Docker build time — no manual sync required.

To regenerate locally after an API change (requires Docker to be running):

cd web
npm run generate:types

This hits http://localhost:3000/swagger/v1/swagger.json and writes src/types/api.generated.ts. Commit the updated file so the contract change is visible in the PR diff.

Tests

dotnet test api/

Architecture

API (api/) — ASP.NET Core (.NET 10), controller + service + repository layers.

• TaxController — validates input, delegates to service
• TaxCalculationService — pure calculation logic, injected via ITaxCalculationService
• Repository pattern for configuration data (ITaxBandRepository, IAccSettingsRepository, IKiwiSaverRateRepository) — currently in-memory, swappable for database persistence
• xUnit tests covering all tax bands, ACC, KiwiSaver, and net pay calculations
• Serves the React SPA from wwwroot/ in Docker via UseStaticFiles() + MapFallbackToFile

Frontend (web/) — React 19 + TypeScript + Vite.

• CSS Modules with CSS custom properties for design tokens
• TanStack Query for API calls with caching
• React Compiler enabled for automatic memoisation
• Strict type-aware ESLint rules (strictTypeChecked + eslint-plugin-react-x)