Is GSTIN the same as GST number?

Yes. GSTIN, GST number and GST registration number all refer to the same 15-character identification number.

Can one PAN have more than one GSTIN?

Yes. A business gets a separate GSTIN for each state it is registered in, and can hold more than one GSTIN in the same state for different business verticals. All of them carry the same PAN.

Does my GSTIN change if I move my shop?

Not if you stay in the same state: you file an amendment to update the address. Moving to a different state needs a new registration with that state's code.

How can I tell if a GSTIN is fake?

Check the state code and PAN pattern, then search it on the GST portal under Search Taxpayer. A fake number either fails the check or shows no record, and a cancelled one shows its status as Cancelled.

GSTIN: the 15-character GST number explained

Updated 11 October 2026

A GSTIN (Goods and Services Tax Identification Number) is the 15-character number given to every business registered under GST. It is built from the state code, the business's PAN, a registration count, the letter Z and a check character. Once you know the pattern, you can read where a business is registered, and spot many fake or mistyped numbers, at a glance.

The structure of a GSTIN

Take the made-up GSTIN 29ABCPK1234D1Z5:

Position	In the example	What it means
1 to 2	29	State code (29 is Karnataka)
3 to 12	ABCPK1234D	PAN of the business or proprietor
13	1	Entity number: the 1st registration of this PAN in this state
14	Z	"Z" by default
15	5	Check character, calculated from the first 14

State codes

The first two digits follow the census state codes. Some common ones:

Code	State or UT	Code	State or UT
03	Punjab	21	Odisha
06	Haryana	23	Madhya Pradesh
07	Delhi	24	Gujarat
08	Rajasthan	27	Maharashtra
09	Uttar Pradesh	29	Karnataka
10	Bihar	32	Kerala
18	Assam	33	Tamil Nadu
19	West Bengal	36	Telangana
20	Jharkhand	37	Andhra Pradesh

If a bill from a Pune shop shows a GSTIN starting with 07 (Delhi), ask why. A mismatch can also mean the wrong type of tax was charged (see CGST, SGST and IGST).

The PAN part

Characters 3 to 12 are the 10-character PAN, so every GSTIN of a business carries the same PAN. Inside the PAN:

the 4th character of the PAN (the 6th of the GSTIN) shows the type of holder: P for an individual, C for a company, F for a firm or LLP, H for a Hindu Undivided Family, T for a trust, A for an association of persons, G for government;
the 5th character is usually the first letter of the surname (for individuals) or of the entity's name.

In our example, "P" tells you the registration belongs to an individual proprietor. Read more about PAN cards.

The entity number and the letter Z

A single PAN can hold several registrations in the same state, for example for separate business verticals. The 13th character counts them: 1 for the first, 2 for the second, up to 9, then the letters A to Z, allowing up to 35 registrations per PAN per state. The 14th character is "Z" for normal registrations.

How the check character works

The last character is a checksum calculated from the first 14 characters with a standard formula. Its job is to catch typing mistakes: change any single character and the checksum almost always stops matching.

Worked example. For 29ABCPK1234D1Z, each character is given a value: digits keep their value and letters run from A = 10 to Z = 35. Starting from the left, characters in odd positions are multiplied by 1 and those in even positions by 2. Each product is split into its quotient and remainder when divided by 36, and the two are added. For the 6th character P (value 25), the product is 50, which gives 1 + 14 = 15. For the 14th character Z (value 35), the product is 70, which gives 1 + 34 = 35.
Adding all fourteen results gives 175. Divide by 36: 175 = 4 × 36 + 31, so the remainder is 31. The check value is 36 minus 31 = 5, so the full GSTIN is 29ABCPK1234D1Z5.
If someone writes 29ABCPK1234D1Z8, the checksum shows it cannot be valid.

A correct checksum only proves the number is well formed. It does not prove the registration exists or is active.

How to verify a GSTIN

Go to gst.gov.in and choose Search Taxpayer, then Search by GSTIN/UIN.
Enter the GSTIN and the captcha.
Check the legal name, trade name, status (Active, Suspended or Cancelled), date of registration, and taxpayer type (Regular or Composition).
Look at the return filing table to see if the business files regularly.

This matters most for businesses. If your supplier's GSTIN is fake or cancelled, or it does not file returns, the invoice will not appear in your GSTR-2B and you could lose the input tax credit. If the supplier is under the composition scheme, it should not be charging GST on its bills at all.

Where a GSTIN must be shown

On every tax invoice, bill of supply, credit note and debit note
On the name board at the entrance of the principal place of business and each additional place of business
On e-way bills and in GST returns

Use our GST calculator to check that the tax on an invoice adds up.