Reviewed by Finin2min Editorial Desk · Last reviewed 10 September 2026
Validate the 15-character GSTIN structure, decode its components and direct the user to official taxpayer verification.
2-minute answer
Validate the 15-character GSTIN structure, decode its components and direct the user to official taxpayer verification.
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Reviewed for currentness, usability and source quality on 10 September 2026. Where an official source changes after this date, the official source prevails.
Validate GSTIN structure
Format result
Enter a 15-character GSTIN.
Element
Decoded value
State code
—
PAN portion
—
Entity number
—
Default character
—
Check character
—
How This Is Calculated
A GSTIN is a 15-character code: the first 2 digits are the state code, the next 10 characters are the PAN of the business, the 13th character indicates the entity/registration number for that PAN in that state, the 14th character is always "Z" by default, and the 15th is a checksum digit calculated from the preceding characters. This tool checks the format and recalculates the checksum to confirm the GSTIN is structurally valid.
Frequently Asked Questions
What do the 15 characters of a GSTIN represent?
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Characters 1-2: state code. Characters 3-12: the business's 10-character PAN. Character 13: entity code (for multiple registrations under the same PAN in a state). Character 14: default "Z". Character 15: a checksum digit, calculated algorithmically from the other 14 characters, used to catch data-entry errors.
Does a valid GSTIN format mean the business is actually registered?
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No. This tool only checks that the GSTIN follows the correct structural format and passes the checksum calculation — it does not confirm the GSTIN is actually active or registered with the GST department. For that, check the GSTIN status directly on the official GST portal.
Why would a GSTIN fail the checksum check?
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A typo anywhere in the 15 characters — a transposed digit, a wrong letter, or a missing character — will almost always cause the checksum calculation to fail, which is exactly the point of the checksum: to catch data-entry mistakes before the GSTIN is used on an invoice or filing.
Source and review trail
Use the current official instrument, portal or regulator publication before acting. This panel separates the category authority from page-specific references.
Scope: Validates the format and checksum of a GSTIN (GST Identification Number) to check it is structurally well-formed, per the 15-character GSTIN structure prescribed under the GST registration rules.
Calculation logic
Check the GSTIN is exactly 15 characters: the first 2 digits are the state code (validated against the list of valid state/UT codes), the next 10 characters are the PAN of the entity (itself following the standard PAN format), the 13th character is the entity/registration count for that PAN in that state, the 14th character is a fixed 'Z' by default, and the 15th character is a checksum digit.
Recompute the checksum digit using the standard GSTIN checksum algorithm (a modulus-36 check-digit calculation over the first 14 characters) and compare it against the 15th character entered — a mismatch indicates the GSTIN is not validly formatted (e.g., a typo).
Inputs and assumptions
This is a structural/checksum validation only — it confirms the GSTIN is well-formed and internally consistent, not that it corresponds to an actually active, currently registered taxpayer.
State code validation uses the current list of state/UT codes as assigned under the GST registration framework.
Exclusions and edge cases
Does not itself verify the GSTIN's live registration status (active/cancelled/suspended) or the registered legal name — for that, the user must separately search the GSTIN on the official GST portal's public search facility.
A structurally valid (checksum-correct) GSTIN is not proof the number is genuinely allotted — always cross-check on the official portal before relying on a GSTIN for a business transaction.