How do I check if a GSTIN is genuine?

Use Search Taxpayer on gst.gov.in and enter the 15-character GSTIN. The portal returns the registered legal name, trade name, registration date, taxpayer type and status. A genuine, usable GSTIN shows status Active and a legal name matching the party you are billing.

What happens if I invoice against a wrong GSTIN?

Your GSTR-1 files the invoice against that number, so it appears in the wrong taxpayer's GSTR-2B or in none. Your actual buyer cannot claim input tax credit until you amend the entry in a later return.

Can I bill a party whose GSTIN is cancelled?

You can sell to them, but not as a B2B supply with their GSTIN on the invoice. A cancelled registration makes it a B2C sale with no input tax credit for the buyer. Check the status date: a GSTIN cancelled after your invoice date does not affect that invoice.

What do the first two digits of a GSTIN mean?

The state code of the registration: 33 is Tamil Nadu, 29 Karnataka, 36 Telangana and so on. Place of supply follows this code, deciding whether the invoice carries CGST plus SGST or IGST.

Does GSTIN verification cost anything?

The GST portal lookup is free but manual. Billing software that verifies through an API typically pays per lookup, which is why caching matters: in Crackers Billing Software a verified GSTIN is stored in your own GST master and never looked up twice.

Verify a customer's GSTIN before you bill them

GST & Accounts · 15 August 2026

A wholesale party phones in an order and reads out their GSTIN. Someone at the counter writes it on a slip, someone else types it into the bill, and the invoice goes out with the consignment. Months later the party calls back, unhappy: the invoice never appeared in their GSTR-2B, and the input tax credit on a lakh of stock is stuck.

The cause is almost always small. A digit misheard on the phone, a GSTIN that was cancelled last year, or a number that belongs to the party's other firm. The fix is cheap too: check the GSTIN once, before the first invoice, and you never have this conversation.

What a wrong GSTIN actually costs

Your buyer loses input tax credit. GSTR-2B is built from what sellers file. An invoice filed against the wrong GSTIN lands in a stranger's 2B, or nowhere, and your buyer cannot claim the 18% they paid you.
Your GSTR-1 needs amendment. Fixing the invoice next month means an amendment entry, questions from the party's accountant, and sometimes a debit-credit note exchange.
A cancelled GSTIN turns B2B into B2C. If the buyer's registration was cancelled before the invoice date, the sale is legally a B2C supply. The tax picture changes and the buyer gets no credit at all.
Repeated mismatches attract notices. A seller whose GSTR-1 keeps failing to match draws attention no trader wants during assessment season.

Reading a GSTIN before you even look it up

The 15 characters carry information on their face. The first two digits are the state code: 33 is Tamil Nadu, 29 Karnataka, 36 Telangana. The next ten characters are the party's PAN. The fifteenth is a checksum, which is why one mistyped digit usually produces an invalid number rather than someone else's.

That state code matters beyond identity. Place of supply follows the buyer's GSTIN, so 33 to 33 is CGST plus SGST, and 33 to anything else is IGST. A misread state code puts the wrong tax on the invoice even when the rest of the number is right.

The manual check on the GST portal

Open gst.gov.in and choose Search Taxpayer, then Search by GSTIN/UIN.
Type the 15-character GSTIN and the captcha.
Read the result: legal name, trade name, registration date, taxpayer type (regular or composition) and, most important, status. Only Active is good news.
Match the legal name against who is actually buying from you. A party ordering under one firm's name and a different firm's GSTIN is the classic setup for a later dispute.

The check takes a minute or two per party. That is fine in July. In the two weeks before Diwali, when new parties appear daily and the counter has a queue, the portal tab quietly stops being opened, and that is exactly when wrong GSTINs get onto invoices.

The composition trap hides in this lookup

The portal result shows taxpayer type. If it says Composition, your buyer cannot claim input tax credit at all, and their large B2B order priced on the assumption of credit may come back for renegotiation. Better to know before the lorry leaves.

Letting the software do it

This is a job software should own. In Crackers Billing Software, the GST invoice form has a Verify GSTIN button next to the buyer's number. One click fetches the registered legal name, trade name, status, PAN and principal address from the GST network, and shows you a field-by-field comparison before anything on the invoice changes.

Each verified GSTIN is saved to your own GST master, so a party you verified in September is answered from your records in October, instantly and without another lookup. New parties get checked because checking is one click; old parties cost nothing because the answer is already in the master.

The same form fills place of supply from the verified state code and switches between CGST/SGST and IGST on its own, so the misread-state-code problem disappears along with the misread GSTIN.

A season rule worth adopting

Verify every new B2B party once, at the first invoice, and re-verify any party who changes their billing name or address. That single habit protects your buyer's credit, keeps your GSTR-1 clean, and takes less time than one amendment would. This article is general information for the trade, not tax advice; confirm your own case with a GST practitioner.

Frequently asked questions

How do I check if a GSTIN is genuine?: Use Search Taxpayer on gst.gov.in and enter the 15-character GSTIN. The portal returns the registered legal name, trade name, registration date, taxpayer type and status. A genuine, usable GSTIN shows status Active and a legal name matching the party you are billing.
What happens if I invoice against a wrong GSTIN?: Your GSTR-1 files the invoice against that number, so it appears in the wrong taxpayer's GSTR-2B or in none. Your actual buyer cannot claim input tax credit until you amend the entry in a later return.
Can I bill a party whose GSTIN is cancelled?: You can sell to them, but not as a B2B supply with their GSTIN on the invoice. A cancelled registration makes it a B2C sale with no input tax credit for the buyer. Check the status date: a GSTIN cancelled after your invoice date does not affect that invoice.
What do the first two digits of a GSTIN mean?: The state code of the registration: 33 is Tamil Nadu, 29 Karnataka, 36 Telangana and so on. Place of supply follows this code, deciding whether the invoice carries CGST plus SGST or IGST.
Does GSTIN verification cost anything?: The GST portal lookup is free but manual. Billing software that verifies through an API typically pays per lookup, which is why caching matters: in Crackers Billing Software a verified GSTIN is stored in your own GST master and never looked up twice.

Sources

This guide is general information for the crackers trade, not legal, tax or safety advice. Rules change by state and by year; confirm the current position with your licensing authority or accountant.