Is the Free Old Tax Regime Calculator API free to use in production apps?

Yes! All FinCalculator REST APIs are completely free, zero-auth, open-CORS, and edge-cached for high performance across global web and mobile applications.

What is the rate limit for /api/v1/income-tax?

Endpoints are cached at the edge for 24 hours. There are no restrictive rate limits for standard web traffic and mobile applications.

Taxation & Salary APIWeb Calculator UI

Free Old Tax Regime Calculator API (2026)

API calculating income tax under Old Tax Regime.

Interactive API Playground & Live Test

GET/api/v1/income-tax

Zero Auth • Open CORS

Query Parameters

incomenumber • required

Gross annual income in ₹

regimestring • optional

old

curl -X GET "https://fincalculator.in/api/v1/income-tax?income=1500000&regime=old" \
  -H "Accept: application/json"

Live JSON Response (HTTP 200 OK)

Click "Execute Live API Request" below...

Request Parameters Schema

Parameter	Type	Required	Description / Notes
income	number	Required	Gross annual income in ₹
regime	string	Optional	old

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