Free GST, tax & invoice tools

Generate invoices, validate GSTINs, find HSN codes, and run GST, TDS & income-tax numbers — accurate, instant, no sign-up. The same engines that power OnGravy's books, built for Indian business owners and their CAs.

Ask a tax question· grounded in OnGravy’s indexed tax knowledge

GST Invoice Generator

Make a GST tax invoice with the CGST/SGST/IGST split done for you — download the PDF.

Income Tax Calculator

Old vs new regime, FY 2026-27 — see which saves you more.

Take-Home Salary Calculator

Turn your CTC into monthly in-hand — PF, PT and deductions done for you.

HRA Exemption Calculator

How much of your HRA is tax-free — the least-of-three rule, computed.

Capital Gains Calculator

STCG/LTCG on shares, mutual funds & property — §111A/112A with the ₹1.25L exemption.

Gratuity Calculator

Your gratuity under the Payment of Gratuity Act — 15/26 formula, ₹20L cap.

Loan EMI Calculator

Monthly EMI, total interest and payable on any loan — instantly.

Project your SIP maturity — invested, estimated returns and final value.

15-year PPF maturity with annual compounding at the current rate.

HSN Code Finder

Search any product or service → its HSN/SAC code and GST rate.

GST Rates by Product

Browse GST rates for common goods & services, 0% to 40%.

GSTIN Validator

Validate a GST number, decode the state, PAN and entity type.

Add or remove GST, with the CGST/SGST/IGST split done for you.

TDS Rate Finder

Rate + amount for 194C, 194J, 194I, 194H and more.

GST Late Fee Calculator

Late fee + 18% interest on a delayed GSTR-3B / GSTR-1.

Advance Tax Calculator

Installment schedule + §234B/234C interest estimate.

GST Registration Checker

Do you need GST registration, e-invoicing, or composition?

Stop calculating. Let your books do it.

OnGravy runs GST, TDS and income tax on your real transactions automatically — and prepares the returns your CA can file.

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