GSTIN checker

How it works

A GSTIN (Goods and Services Tax Identification Number) is the number a business gets when it registers for GST. It has 15 characters, in four parts: a State code, a PAN (Permanent Account Number), an entity code and a check character. Rule 10 of the CGST Rules (the Central Goods and Services Tax Rules, 2017) sets these parts.

The checker looks at each part in turn. If something is wrong, it says which character and how to fix it. It doesn’t look the GSTIN up anywhere, so it can’t tell you whether the business is registered.

What the 15 characters mean

The check character

The last character is worked out from the first 14 with a fixed sum. Change any one character, the last one included, and the check fails. It catches every single mistyped character and most swaps of two characters next to each other, but not every mix of two or more mistakes. It can show that a character is wrong, but not which one.

A worked example

Here is a made-up GSTIN, built from the made-up PAN ABCDE1234F. It belongs to no one: 02ABCDE1234F1ZC.

1. Characters 1 and 2 are 02, the State code for Himachal Pradesh.
2. Characters 3 to 12 are ABCDE1234F: five letters, four numbers, then a letter, as a PAN should be.
3. Character 13 is 1, which isn’t zero, and character 14 is Z.
4. The check character worked out from the first 14 is C, and character 15 is C. So the GSTIN is written correctly.

Now the same made-up GSTIN with one typing mistake at a time:

• The letter I typed for the number 1: 02ABCDEI234F1ZC. The checker says:

  Characters 3 to 12 are the PAN: five letters, four numbers, then a letter. Character 8 should be a number, but it is “I”. If you meant the number 1, type that instead.

• The 3 and the 4 swapped: 02ABCDE1243F1ZC. Every part still has the right shape, but the check character no longer matches, so the checker says:

  The last character is a check character worked out from the first 14, and it doesn’t match them, so at least one character is wrong. Check each one against the GSTIN you were given, looking out for zero and the letter O, one and the letter I, five and S, and eight and B.

What the checker can’t tell you

• Whether the business is registered, or whether its registration is still active. A GSTIN can be written correctly and still be made up or cancelled. To check, search for it on the GST portal’s Search Taxpayer page.
• Whether a GSTIN with a TAN in it is right. Rule 10 allows a TAN (Tax Deduction and Collection Account Number) in characters 3 to 12 instead of a PAN. The checker doesn’t check those.

The State codes

The checker knows these 39 codes, from the official sources listed at the end of this page. A GSTIN that starts with a code marked “no longer used” gets a message asking you to check that you have the current one.