Regulatory & Tax

GSTIN

Goods and Services Tax Identification Number — a 15-character ID assigned to every GST-registered business in India.

The GSTIN is structured as: 2 digits for state code + 10 digits for PAN + 1 digit for entity number + 1 default 'Z' + 1 check digit. So `29AAACR5055K1ZK` decodes as Karnataka (29), PAN AAACR5055K, first entity, Z default, K check.

Every business with annual turnover above ₹20L (₹40L for goods sellers, ₹10L for special-category states) must register and get a GSTIN. Marketplace sellers must register from their first sale, regardless of turnover.

The GSTIN is what appears on invoices, what your customers verify before claiming Input Tax Credit, and what determines your filing obligations.

India context

Verifying GSTIN before issuing a B2B invoice is critical — wrong GSTIN means your customer can't claim ITC, and they'll come back to ask you to reissue. Tools like the GST portal's verify-GSTIN API + cross-checking the legal name should be standard for any B2B SMB.

Examples

  • A Karnataka business with PAN AAACR5055K gets GSTIN 29AAACR5055K1ZK.
  • A multi-state business gets one GSTIN per state where it operates.
  • Composition scheme businesses use a different format ('1' as 14th char) than regular taxpayers.

FAQ

Can I have multiple GSTINs?

Yes — one per state where you have a place of business. A pan-India ecom seller registered in Karnataka, Maharashtra, and Delhi will have 3 GSTINs.

How do I verify a GSTIN?

Use the official GST portal's 'Search Taxpayer' tool, or programmatically via the GSTN API. Always cross-check the legal name with the customer's purchase order.

What if my GSTIN is suspended?

You can't issue tax invoices or claim ITC during suspension. Causes: failure to file 6 consecutive returns, incorrect filings, or fraud detection. Resolve via the GST portal.

Related concepts

GSTPANGSTR-1Input Tax Creditplace of supply

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Related glossary entries

GSTR-1 — Monthly (or quarterly) statement of outward supplies — every B2B and B2C invoice your business issued in the period.GSTR-3B — Monthly self-declared summary of all outward and inward supplies and tax liability — the form you actually pay GST against.ITC (Input Tax Credit) — Credit you can claim for GST already paid on business purchases — reduces what you owe in GST.PAN — Permanent Account Number — 10-character alphanumeric ID issued by Income Tax Department, used as universal taxpayer ID.Place of Supply (GST) — GST rule that determines which state/UT gets the tax on a transaction — drives whether CGST+SGST or IGST applies.

More in Regulatory & Tax

DPDP ActGSTR-1GSTR-3BRCM (Reverse Charge Mechanism)ITC (Input Tax Credit)RERAFSSAIHSN Code
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