GSTIN Validator
Check a GST number's format & checksum
Reviewed by the PaisaTools Editorial Team · Last reviewed September 2026 · Applicable to FY 2026-27 (AY 2027-28)
How to use: Paste or type a 15-character GSTIN — we check the format and checksum instantly.
Example27AAPFU0939F1ZV → valid · State: Maharashtra · PAN: AAPFU0939F
Every GSTIN follows a fixed structure: SS PPPPPPPPPP E Z C — a 2-digit state code, the 10-character PAN, a 1-digit entity code (how many registrations the PAN has in that state), the letter Z, and a checksum.
The checksum is computed from the first 14 characters using the official GSTN mod-36 algorithm, so a single mistyped character almost always fails the check — which makes this a quick way to catch errors before you put a GSTIN on an invoice.
Validates the 15-character GSTIN structure notified under the CGST Act — state code, PAN, entity code and the final checksum digit computed with the official mod-36 algorithm used by the GST Network.
- Validates the structure and checksum only — not whether the GSTIN is active on the GST portal.
- What makes a GSTIN valid?
- A GSTIN is 15 characters: a 2-digit state code, the 10-character PAN of the business, a 1-digit entity code, the letter 'Z', and a final checksum character. This tool checks the pattern and recomputes the checksum to confirm it matches.
- Does a 'valid' result mean the GSTIN is real and active?
- No. This confirms the format and checksum are mathematically correct — it can't tell you if the number is actually registered or currently active. For live registration status, search the number on the official GST portal.
- What is the PAN inside a GSTIN?
- Characters 3 to 12 of a GSTIN are the holder's PAN (Permanent Account Number). So the GSTIN is essentially the PAN wrapped with a state code, entity code and checksum.
- What does the state code mean?
- The first two digits identify the state or union territory of registration — e.g. 27 is Maharashtra, 29 is Karnataka, 07 is Delhi. A business has a separate GSTIN per state it operates in.
- Is anything I paste sent anywhere?
- No. The validation runs entirely in your browser — the GSTIN you enter never leaves your device.