# GSTIN format explained: what each of the 15 characters means

URL: https://indialookup.net/blog/gstin-format-explained/
Published: 2026-10-05 · Updated: 2026-10-05 · Category: Business

> A GSTIN is not a random code - it carries the state, the PAN, a registration count and a check digit. Here is how to read one and spot a fake.

Every business registered under GST holds a 15-character **GSTIN** (Goods and Services Tax Identification Number) for each state it operates in. It looks like a random string, but every position means something - which is why you can catch a lot of fake or mistyped numbers before you even look them up.

Take `29AAACI1234F1ZY` (a made-up number with a valid check digit) as an example.

## The five parts

| Positions | Example | What it is |
| --- | --- | --- |
| 1-2 | `29` | State code - 29 is Karnataka |
| 3-12 | `AAACI1234F` | The business's PAN |
| 13 | `1` | Registration count under that PAN in the state |
| 14 | `Z` | Always the letter Z |
| 15 | `Y` | Check digit |

### State code (1-2)

The first two digits are the GST state code: 01 is Jammu & Kashmir, 27 Maharashtra, 29 Karnataka, 33 Tamil Nadu, up to 38 for Ladakh. 97 is "Other Territory" and 99 is the Centre.

Registration is per state, so a company with branches in five states holds five GSTINs on the same PAN. When you verify a supplier, check the GSTIN for **the state the invoice is raised from**.

### PAN (3-12)

Characters 3 to 12 are the PAN of the business. Its **fourth letter** tells you the type of entity:

- **C** - company
- **P** - individual (a proprietorship)
- **F** - firm or LLP
- **H** - Hindu Undivided Family
- **T** - trust

If an invoice says "Pvt Ltd" but the PAN's fourth letter is P, the GSTIN belongs to an individual, not the company named on the invoice.

### Registration count (13)

Position 13 counts registrations under that PAN in that state: 1 to 9, then A to Z. Most businesses have a 1 here.

### The fixed Z (14)

Position 14 is always Z. Anything else is a typo or a made-up number.

### Check digit (15)

The last character is computed from the first fourteen with a mod-36 checksum. Change any one character and the check digit stops matching - so a number that "looks right" but was typed from memory usually fails this test.

[GST on IndiaLookup](https://indialookup.net/gst/)

## Format is not status

A GSTIN can be perfectly formed and still useless to you. The registry also records whether the registration is **Active**, **Suspended** or **Cancelled**, the date it was granted, the legal and trade names, and every place of business. Input tax credit depends on the supplier being registered and filing, so a cancelled GSTIN on an invoice is a problem for your books, not just theirs.

That is why the check has two steps:

1. Read the format - state, PAN type, the Z, the check digit.
2. Look the number up in the GST registry and confirm the status and the legal name match the invoice.

## Going further

The PAN inside the GSTIN connects to other registers. A company (fourth letter C) also has a CIN on the MCA register - a [company lookup](/mca) shows its directors and status. Small businesses often hold a Udyam registration too, which an [MSME lookup](/msme) can confirm.

## Check it yourself

- [GST](https://indialookup.net/gst/): Verify any GSTIN - legal name, status, taxpayer type, jurisdiction and every place of business from the GST registry - plus a guide to GST registration.
- [Company Lookup](https://indialookup.net/mca/): Look up an Indian company by CIN or a director by DIN - status, ROC, registered office, filed financials and board. Guide to CIN, DIN, MCA21 and company status.
- [MSME Lookup](https://indialookup.net/msme/): Check any Udyam Registration Number - enterprise name, micro/small/medium category, owner, address, plants and NIC codes. Guide to Udyam rules and 2025 limits.

Related: [All articles](https://indialookup.net/blog/) · [llms.txt](https://indialookup.net/llms.txt)