GSTIN validator: check any GST number’s format and check digit
A GSTIN (Goods and Services Tax Identification Number) is the 15-character number every GST-registered business in India prints on its invoices. This GSTIN validator checks that a number is built correctly — the state code, the PAN inside it, the entity number, the fixed letter Z and the final check character computed with the official mod-36 algorithm — and decodes each part so you can see the state of registration, the PAN and what kind of taxpayer the PAN belongs to.
Use it before you accept a supplier’s invoice, enter a customer in your accounts, or file GSTR-1: a mistyped GSTIN fails the structural check instantly, which saves a rejected return or a blocked input tax credit. The bulk mode validates hundreds of numbers pasted one per line and exports the results as CSV. Everything runs in your browser; nothing is sent to a server.
A valid format does not prove the number is registered or active. Confirm registration status and the legal name on the GST portal’s “Search Taxpayer” page, which this tool cannot query.
How to use the GSTIN Validator
- Type or paste a GSTIN in the GSTIN box — spaces and lower case are tidied up automatically.
- Read the verdict, the colour-coded structure and the decoded State, PAN, PAN holder type and Entity number.
- If the number is invalid, the checklist names the failing rule and shows the check character the number should end with.
- For a list, switch to Bulk, paste one GSTIN per line and press Validate list.
- Press Download CSV to save the results with state, PAN and reason columns.
GSTIN Validator features
Official check character
Implements the GSTN mod-36 algorithm: weights 1 and 2 alternate across the first fourteen characters, the digit sums are added, and the remainder sets the fifteenth character.
Full decode
State name from the two-digit code (all 38 codes plus 97 and 99), the embedded PAN with its holder type, and the entity number that distinguishes multiple registrations under one PAN.
Clear failure reasons
Wrong length, unknown state, malformed PAN, zero entity number, missing Z or a bad check character — each is named, with the expected character.
Bulk validation with CSV export
Paste a column from your ledger and get a table and downloadable CSV of valid and invalid numbers.
Private
Validation happens entirely on your device; the tool makes no network requests.
GSTIN format explained
Take 27AAPFU0939F1ZV. Its fifteen characters break down like this:
| Position | Example | Meaning |
|---|---|---|
| 1–2 | 27 | State code of the registration (27 = Maharashtra) |
| 3–12 | AAPFU0939F | The taxpayer’s PAN; the 4th PAN letter F means a firm |
| 13 | 1 | Entity number: how many registrations this PAN has in the state (1–9, then A–Z) |
| 14 | Z | Fixed letter Z, reserved for future use |
| 15 | V | Check character computed from the first fourteen |
How the GSTIN check digit is calculated
Because a single mistyped character changes the sum, almost every typo — and every transposition of two neighbouring characters of different weight — produces a different check character and is caught.
- Map each of the first 14 characters to a number: 0–9 stay as they are, A = 10 … Z = 35.
- Multiply the characters at odd positions (1st, 3rd, 5th …) by 1 and those at even positions by 2.
- For each product add its quotient and remainder when divided by 36 (so 2 × 35 = 70 becomes 1 + 34 = 35).
- Add everything up, take the total modulo 36, subtract from 36 and take modulo 36 again.
- Map the result back to a character: that is the 15th character. For 27AAPFU0939F1Z the result is V.
GST state codes
01 Jammu and Kashmir · 02 Himachal Pradesh · 03 Punjab · 04 Chandigarh · 05 Uttarakhand · 06 Haryana · 07 Delhi · 08 Rajasthan · 09 Uttar Pradesh · 10 Bihar · 11 Sikkim · 12 Arunachal Pradesh · 13 Nagaland · 14 Manipur · 15 Mizoram · 16 Tripura · 17 Meghalaya · 18 Assam · 19 West Bengal · 20 Jharkhand · 21 Odisha · 22 Chhattisgarh · 23 Madhya Pradesh · 24 Gujarat · 26 Dadra and Nagar Haveli and Daman and Diu · 27 Maharashtra · 29 Karnataka · 30 Goa · 31 Lakshadweep · 32 Kerala · 33 Tamil Nadu · 34 Puducherry · 35 Andaman and Nicobar Islands · 36 Telangana · 37 Andhra Pradesh · 38 Ladakh · 97 Other Territory · 99 Centre Jurisdiction. The state code also decides whether a sale is intra-state (CGST + SGST) or inter-state (IGST) — the GST invoice validator checks that, and the GST calculator splits the tax.
GSTIN Validator FAQ
Does a valid GSTIN mean the business is registered?
No. The GSTIN validator confirms the number is structurally correct and its check character matches. Whether it is active, cancelled or belongs to the business named on the invoice must be checked on the GST portal.
Why does the GSTIN contain a PAN?
GST registration is PAN-based. Characters 3 to 12 are the taxpayer’s PAN, so one PAN can hold registrations in several states, each with its own state code and entity number.
What is the 13th character of a GSTIN?
The entity or registration number: 1 for the first registration of that PAN in the state, 2 for the second and so on; after 9 it continues with letters A to Z.
Can the 14th character be something other than Z?
Under the current numbering scheme it is always Z, kept for future use. A number with another letter there fails validation.
What about UINs for embassies and TDS deductors?
Unique Identification Numbers issued to UN bodies, embassies and some government deductors follow a different pattern and will not pass this check; validate those on the GST portal.
Is my data uploaded?
No. The check runs in your browser, and the bulk CSV is generated on your device. Use the PAN card validator to check the PAN on its own.