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GSTIN Validator & Decoder 2026

Every GST Identification Number (GSTIN) follows a strict 15-character structure with a built-in check digit that can be verified mathematically, without calling any external API. This free tool validates the format and checksum of any GSTIN and decodes it into its components — the state code and name, the embedded 10-character PAN of the business, the registration sequence number for that PAN in the state, and the final checksum digit. Use it to quickly catch typos in vendor GSTINs before they cause ITC mismatches or e-invoice rejections. All calculations run locally in your browser — no GSTIN data is sent anywhere.

Enter GSTIN

0/15 characters. Validation runs entirely in your browser — nothing is sent to a server.

Validation Result

Enter a GSTIN above to validate and decode it.

How GSTIN is structured

• Characters 1–2: State code (as per Indian Census 2011)

• Characters 3–12: 10-character PAN of the business

• Character 13: Entity/registration number for that PAN in the state (1–9, then A–Z)

• Character 14: Fixed as "Z" by default

• Character 15: Check digit computed using a mod-36 checksum algorithm

This tool validates format and checksum only. It does not confirm the GSTIN is active or verify it against the GST portal — always cross-check on the official GST portal before relying on it for filings.

How It Works

  1. 1

    Paste the 15-character GSTIN

    The tool checks the overall format — 2-digit state code, 10-character PAN, 1-character entity code, a fixed "Z", and a final check digit.

  2. 2

    The checksum is recomputed and compared

    Using the mod-36 checksum algorithm on the first 14 characters, the tool derives the expected 15th character and compares it against what was entered.

  3. 3

    The GSTIN is decoded into its components

    State name, embedded PAN, PAN holder type, and registration sequence number are shown instantly for a valid GSTIN.

Stop Chasing Vendor GSTIN Errors Manually

TaxZeo validates client and vendor GSTINs automatically and flags mismatches before they hit your GSTR filings.

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Frequently Asked Questions

What is a GSTIN?+
GSTIN (Goods and Services Tax Identification Number) is a unique 15-character alphanumeric code assigned to every business registered under GST in India. It encodes the state of registration, the business PAN, a registration sequence number, and a check digit.
How is the GSTIN checksum calculated?+
The 15th character of a GSTIN is a check digit computed using a mod-36 checksum algorithm over the first 14 characters, similar to the algorithm used for PAN and other Indian identifiers. This tool implements that algorithm to verify whether a GSTIN is internally consistent.
Does a valid checksum mean the GSTIN is active?+
No. A passing checksum only confirms the number is correctly formatted and mathematically valid — it does not confirm the GSTIN is currently active, registered, or belongs to a real taxpayer. Always cross-check active status on the official GST portal (services.gst.gov.in) before relying on it for invoicing or ITC claims.
What do the first two digits of a GSTIN mean?+
The first two digits are the state code as per the 2011 Census of India — for example, 27 for Maharashtra, 07 for Delhi, and 33 for Tamil Nadu. This tool decodes the state name automatically.
Can I extract the PAN from a GSTIN?+
Yes. Characters 3 to 12 of a GSTIN are exactly the 10-character PAN of the business or individual holding the registration. This tool extracts and displays it, along with the PAN holder type indicated by the 4th PAN character.

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