A GSTIN has 15 characters: a 2-digit state code, the holder's 10-character PAN, one character for the registration number under that PAN in the state, the letter Z, and a check digit calculated from the first 14 characters. If any part is wrong, the GSTIN is wrong. A correct format does not prove that the GSTIN is active or belongs to the business you are dealing with: for that, check the live record on the GST portal or FundRaksha Trust.
The 15 characters explained
| Position | What it is | Example (27AAPFU0939F1ZV) |
|---|---|---|
| 1-2 | State or territory code where the registration is | 27 = Maharashtra |
| 3-12 | PAN of the business or proprietor | AAPFU0939F |
| 6 (4th of PAN) | Type of PAN holder | F = firm or LLP |
| 13 | Number of the registration under this PAN in this state (1-9, then A-Z) | 1 = first registration |
| 14 | Z by default for regular taxpayers | Z |
| 15 | Check digit | V |
State codes follow the census list: 07 Delhi, 09 Uttar Pradesh, 19 West Bengal, 24 Gujarat, 27 Maharashtra, 29 Karnataka, 33 Tamil Nadu, 36 Telangana, 37 Andhra Pradesh, and so on, with 97 for Other Territory. The 5th character of the PAN is usually the first letter of the surname or name, which is a quick sense-check against the business name.
How the check digit works
Each of the first 14 characters is turned into a number from 0 to 35 (digits 0-9 are themselves, A is 10, B is 11 up to Z at 35). Working from the right, the values are multiplied alternately by 2 and 1; each product is split into its quotient and remainder by 36 and the two are added; all of these are summed. The check digit is the character for (36 − sum mod 36) mod 36. The validator does this for you and shows the digit it expects.
Example: change one letter in 27AAPFU0939F1ZV to 27AAPFU0939F1ZX and the validator reports that the check digit should be V. A buyer who reads out a number over the phone with one wrong character is caught here, before the invoice is raised.
Why a valid format is not enough
Anyone can compute a valid check digit, so a made-up GSTIN can pass this test. The number may also be real but cancelled or suspended, or belong to a different company from the one placing the order. Before you deliver on credit, confirm three things on the live record: the status is Active, the legal and trade name match the purchase order, and returns are being filed. Search Taxpayer on the GST portal shows this, one GSTIN at a time. Read how to check a GST number is active and what each status means.
FundRaksha Trust shows the live status, names, registration date and filing record together, so you can decide on credit terms with the facts in front of you.
Special GSTIN formats
This validator is built for the regular 15-character GSTIN. A few registrations look different: UINs for embassies and UN bodies, TDS and TCS registrations of government departments and e-commerce operators, and registrations of non-resident online service providers. If one of these fails a check here, confirm it on the GST portal rather than assuming it is fake.