Tools
GSTIN validator: check a GST number and read its state and PAN
Paste a GSTIN from a purchase bill or a customer's letterhead. The validator checks the format and the check character, then shows the state and the PAN inside it.
In short
This free GSTIN validator from SimpleERP checks that a GST number has the right 15-character format and check digit, and reads the state code and PAN from it. It runs the same GSTIN check SimpleERP applies when you save a customer or supplier.
How to use it
Spaces and lower-case letters are fine; the validator trims and capitalises before it checks.
Paste the GSTIN
All 15 characters, such as 33AAACL1234A1ZG.
Read the verdict
Valid format, or the exact problem: wrong length, a letter where a digit belongs, or a check character that does not match.
Check the state and PAN
The first two digits name the state, and characters 3 to 12 are the PAN. Even a mistyped GSTIN shows a state guess, so you can see where it went wrong.
What is each character of a GSTIN?
It is 15 characters, not 16; a 16th character is always a typo. Each position has a job, as notified; check the current rules for special registrations such as TDS deductors and non-resident taxpayers, which follow a different pattern.
- Characters 1 to 2: the GST state code, such as 33 for Tamil Nadu or 29 for Karnataka.
- Characters 3 to 12: the holder's PAN.
- Character 13: the registration number for that PAN in that state, 1 for the first, then 2 to 9 and A to Z.
- Character 14: Z by default.
- Character 15: a check character computed from the first 14, which catches most single typos.
Illustration of GST tax invoice INV-2026-27-0213 to Ravi Stores with CGST 9% and SGST 9%, round off, a UPI QR code and the amount in words.
Does a valid format mean the GSTIN is registered?
No. A valid format and check character mean the number could exist. Whether it is active, cancelled or suspended is only on the GST portal's Search Taxpayer page.
- Use the validator to catch typos before you save a supplier or print an invoice.
- Use the [GST portal](https://www.gst.gov.in/) to confirm a new supplier is active before you rely on input tax credit from them.
- Match the PAN in the GSTIN against the PAN on the supplier's documents.
Do this automatically in SimpleERP
SimpleERP runs the same check every time a GSTIN is typed into a customer, supplier or your own business profile, and uses the state code to decide the tax on every invoice.
- A wrong GSTIN is stopped at entry, with the reason shown under the field.
- The state fills itself from the first two digits.
- Place of supply for each invoice starts from the customer's state, so CGST and SGST or IGST is chosen for you.
Illustration of the keyboard-first invoice editor with a focused line, live tax totals and shortcut hints.
The maths
How it is calculated
The check character is a mod-36 checksum over the first 14 characters.
- Turn each character into a value: 0 to 9 stay as they are, A is 10, B is 11, up to Z at 35.
- Multiply the values in odd positions by 1 and in even positions by 2.
- For each product, add its quotient and remainder when divided by 36, and sum them all.
- The check value is (36 − sum mod 36) mod 36, turned back into a character.
Example
Worked example
Lakshmi Steel Furnitures, Coimbatore. Its GSTIN 33AAACL1234A1ZG reads like this.
| Characters | Value | Meaning |
|---|---|---|
| 1 to 2 | 33 | Tamil Nadu |
| 3 to 12 | AAACL1234A | PAN; the fourth letter C marks a company |
| 13 | 1 | First registration for this PAN in Tamil Nadu |
| 14 | Z | Default |
| 15 | G | Check character: matches, so the format is valid |
Change the last character to 5 and the validator reports a check character mismatch, while still showing Tamil Nadu and PAN AAACL1234A.
Honest limits
What this validator does not do
- It does not look the GSTIN up on the GST portal, so it cannot tell you the legal name or whether the registration is active.
- Special GSTINs for TDS deductors, UN bodies and non-resident online service providers follow other patterns and may show as invalid.
FAQ
Questions, answered
Can a GSTIN be checked without the portal?
The format and the check character can, which catches most typos; this validator does that. Whether the GSTIN is active and whose it is can only be confirmed on the GST portal's Search Taxpayer page.
How do I find the state from a GST number?
Read the first two digits. They are the GST state code: 33 is Tamil Nadu, 29 is Karnataka, 27 is Maharashtra and 07 is Delhi.
Is the PAN part of the GSTIN?
Yes. Characters 3 to 12 of a regular GSTIN are the holder's PAN, so one business registered in two states has two GSTINs with the same PAN.
Why is the 14th character of a GSTIN always Z?
It is a default character in the current format, reserved for future use. A GSTIN with any other letter there fails the format check.
Related
Keep reading
GST billing
Tax invoices with CGST, SGST or IGST by place of supply, HSN on every line and a UPI QR on the print.
Read moreGSTIN
The 15-character GST number of a registered business: state code, PAN, entity number, check digit.
Read moreGST invoice format
A GST tax invoice format with every rule 46 field, as a free Excel, Word and PDF download.
Read more
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