GST Invoice Validator

GST invoice validator: catch invoice mistakes before they cost input credit

A tax invoice that breaks the GST rules can be rejected by your customer, mismatch in GSTR-2B, or block input tax credit. This GST invoice validator takes the fields from an invoice — supplier and recipient GSTIN, invoice number and date, place of supply, and each line item’s HSN, taxable value, rate and tax — and runs them through the checks an auditor would: both GSTINs must pass the check-character test, the tax must be CGST + SGST for an intra-state supply and IGST for an inter-state one, every rate must be one that exists on the invoice date, the HSN must have enough digits, and the totals must add up.

Type the fields, or paste the invoice text and let the tool pick out the GSTINs, number, date and place of supply. The result is a pass / warn / fail checklist that names each problem. Everything runs in your browser; nothing is uploaded. It checks structure and arithmetic, not whether the supplier is actually registered — confirm that on the GST portal.

How to use the GST Invoice Validator

1. Enter the Supplier GSTIN and, for a B2B invoice, the Recipient GSTIN — or open the paste box and press Fill fields from text.
2. Pick the Place of supply, type the Invoice number and Invoice date, and choose the Financial year the series belongs to.
3. Add each line item with its HSN or SAC, taxable value, rate and the CGST, SGST or IGST printed on the invoice; press Fill tax from rates to see what the tax should be.
4. Enter the Invoice total as printed and read the checklist — every failed item names the rule and the expected figure.
5. Fix the invoice (or ask the supplier to) and re-check until all checks pass.

GST Invoice Validator features

What a valid GST tax invoice must contain (Rule 46, CGST Rules)

• Supplier’s name, address and GSTIN, and the recipient’s GSTIN for B2B supplies (name and address for B2C above ₹50,000).
• Invoice number: a consecutive serial of up to 16 characters — letters, numerals, hyphen or slash — unique for the financial year.
• Date of issue, and the place of supply with the state name for inter-state supplies.
• HSN or SAC code for each item: 4 digits if aggregate turnover is up to ₹5 crore (B2B), 6 digits above ₹5 crore, 8 digits for exports.
• Description, quantity, taxable value, rate and amount of tax — shown as CGST + SGST/UTGST for intra-state and IGST for inter-state supplies — and whether tax is payable on reverse charge.
• Signature of the supplier, and the IRN and QR code where e-invoicing applies (turnover above ₹5 crore).

Worked example and the GST rates since September 2025

The default invoice shows a Maharashtra supplier selling a laptop (HSN 847130, ₹50,000) and an installation service (SAC 998313, ₹8,000) to a Maharashtra customer. Because the place of supply is Maharashtra, each line carries 9% CGST and 9% SGST: ₹4,500 + ₹4,500 and ₹720 + ₹720. Taxable ₹58,000 + tax ₹10,440 = ₹68,440. Change the place of supply to Karnataka and the same invoice must show 18% IGST (₹9,000 and ₹1,440) with no CGST or SGST; the total is unchanged. Use the GST calculator for quick splits and the GSTIN validator to inspect either number on its own.

From 22 September 2025 the GST Council replaced the four-slab structure with two main rates, 5% and 18%, plus a 40% rate for a short list of luxury and sin goods; 0%, 0.25% (rough diamonds), 1.5% (cut diamonds) and 3% (gold, silver, jewellery) continue. The 12% and 28% slabs no longer apply, except that tobacco, pan masala and similar products stay at 28% plus compensation cess until notified. The validator applies the slab list that matches the invoice date.

Common invoice errors this tool catches

• IGST charged to a customer in the supplier’s own state (or CGST + SGST on an inter-state sale) — the most frequent cause of credit mismatches.
• CGST and SGST that are not exactly half of the rate each, or a rate like 12% used after it was withdrawn.
• Invoice numbers longer than 16 characters or containing “#”, spaces or other symbols.
• An invoice dated in a different financial year from its series, or dated in the future.
• A 4-digit HSN where 6 digits are required, or a non-numeric code.