How to check GSTIN validity

Why it matters

• Selling: a wrong buyer GSTIN in GSTR-1 sends their credit to someone else, or nowhere. You will have to amend it.
• Buying: ITC is available only from a registered supplier whose invoice appears in your GSTR-2B. A cancelled or fake GSTIN means no credit, and possibly a notice.
• Composition suppliers: they cannot charge GST. If one does, you cannot claim that tax.

Step 1: check the format

The example above is made up for illustration. Quick format checks: 15 characters; state code matches the address; characters 3–12 follow PAN's pattern (five letters, four digits, one letter); 14th character is usually Z. The last character is a checksum, so a single typing error usually fails validation on the portal. More in how to read a GSTIN and the GST state codes list.

Step 2: search on the GST portal

1. Go to gst.gov.in. Without logging in, open Search Taxpayer, then Search by GSTIN/UIN.
2. Enter the GSTIN and the captcha.
3. Read the result: legal name, trade name, effective date of registration, constitution of business, taxpayer type, status and principal place of business.
4. Open the return filing details to see whether GSTR-1 and GSTR-3B have been filed recently.

You can also search by PAN to see all GSTINs a business holds in different states, which helps when a customer gives you the wrong branch's GSTIN.

Reading the result

What to ask a new supplier or buyer

Before the first transaction, ask for:

• A copy of the GST registration certificate, showing legal name, GSTIN and address.
• The GSTIN of the specific branch or state that will bill or receive the goods.
• Whether they are a regular or composition taxpayer.
• For suppliers, a sample invoice, so you can see that the name, GSTIN and HSN appear correctly.

Then compare each item with the Search Taxpayer result. If the certificate says one address and the portal shows another, ask. A trader in Surat, for example, may hold registrations in Gujarat and Maharashtra under the same PAN; the GSTIN on your invoice must be the one for the state the goods are billed from or to.

When to check

• When creating a new party master, every time.
• Before a large first order from a new supplier.
• Periodically for regular suppliers, say quarterly, to catch cancellations.
• When a supplier's invoices stop appearing in your GSTR-2B.

Common mistakes

• Copying a GSTIN from an old visiting card after the business moved or re-registered.
• Using the head office GSTIN for a branch in another state.
• Typing O for 0 or I for 1.
• Creating two party masters for the same buyer with different GSTINs, so ledgers split.

This is general information, not tax advice.

Keeping GSTINs right in Tally and Cashflow OS

The GSTIN lives in the party ledger in TallyPrime. Cashflow OS syncs party ledgers, so you can check a party's GSTIN and state from the phone, and if writing back is switched on, staff can create or alter a party ledger with its GSTIN from the app; Tally validates the entry. The portal lookup itself is done on gst.gov.in.