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Glossary · GST & Billing

What is GSTIN?

GSTIN meaning — the 15-digit GST Identification Number — its format, who needs one, and how to verify a GSTIN on the GST portal.

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GSTIN — meaning

GSTIN (Goods and Services Tax Identification Number) is a unique 15-digit alphanumeric number assigned to every entity registered under GST.

What is a GSTIN?

A Goods and Services Tax Identification Number (GSTIN) is a unique 15-character identifier issued to every taxpayer registered under GST. It replaced multiple state-level tax registration numbers with one PAN-linked, state-specific number used across all GST compliance — invoicing, returns, and e-way bills/e-invoices.

GSTIN format

  • The first 2 digits represent the state code.
  • The next 10 characters are the taxpayer's PAN.
  • The 13th character indicates the registration/entity number for that PAN within the state.
  • The 14th character is typically "Z" by default, and the 15th is a checksum digit.

Who needs a GSTIN and how to verify

  • Businesses whose turnover crosses the GST registration threshold, or who are otherwise required to register under GST law (such as those making inter-state supplies or under reverse charge), must obtain a GSTIN.
  • A business can verify any counterparty's GSTIN for authenticity directly on the GST portal before processing a transaction or claiming input tax credit.

Common mistakes

  • Quoting a supplier's GSTIN without verifying it on the GST portal, risking input tax credit issues if the registration is invalid or cancelled.
  • Using the wrong state-code GSTIN when a business has registrations in multiple states.
  • Not updating invoices and records when a GSTIN is cancelled or a business shifts from regular to composition registration.

Sources

Last updated 2026-10-12.

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Related terms

Tax InvoiceA GST tax invoice is the primary document a registered supplier issues for a taxable supply of goods or services, containing the prescribed details needed for GST compliance and the recipient's input tax credit.E-InvoiceE-invoicing under GST is the process of electronically authenticating B2B invoices through the government's Invoice Registration Portal, which issues a unique Invoice Reference Number (IRN) and QR code.Composition SchemeThe GST Composition Scheme is an optional, simplified scheme for small taxpayers to pay GST at a fixed, lower percentage of turnover instead of regular GST rates, with simpler compliance.

GSTIN — FAQs

How many digits does a GSTIN have?+

A GSTIN is a 15-character alphanumeric number: 2 digits for the state code, 10 characters for PAN, 1 for entity code, 1 default character, and 1 checksum digit.

How do I verify a GSTIN?+

You can verify any GSTIN's validity and registration details using the 'Search Taxpayer' tool on the official GST portal, gst.gov.in.

Is GSTIN the same as PAN?+

No, but a GSTIN is derived from and embeds the taxpayer's PAN as its middle 10 characters — the full GSTIN also identifies the state and registration number.

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