Is a GST number the same as a PAN number?

No. Your PAN, issued by the Income Tax Department, sits inside the GSTIN as characters 3 to 12, but the GSTIN is a separate registration. One PAN can hold several GSTINs, one for each state where the business registers. The PAN part stays identical across all of them.

Do you get a different GSTIN in each state?

Yes. Section 25(1) of the CGST Act requires registration in every state or Union Territory where you're liable, and each registration gets its own GSTIN. The first two digits change to that state's code, while your PAN in the middle stays the same.

Can you put your ARN on invoices while the GSTIN is pending?

No. Rule 46 of the CGST Rules requires a tax invoice to show the supplier's GSTIN, and an ARN is only an application reference. Once your certificate arrives, Section 31(3)(a) of the CGST Act lets you issue revised invoices within one month for sales made since your registration's effective date.

Is an ARN issued only for GST registration?

No. The GST portal issues an ARN as an acknowledgement for many filings. CBIC's GST FAQs say one is generated when a GSTR-7 return is filed, and a Letter of Undertaking for exports counts as accepted once its ARN is generated. Always note which filing an ARN belongs to.

Your TRN expired before you submitted. What now?

You'll have to start again. The portal purges an unsubmitted TRN and its saved details after 15 days, so fill Part A afresh to get a new TRN. Keep your documents ready before you begin, and submit Part B well inside the new 15-day window.

GSTIN vs ARN vs TRN in India: 15-Digit GST Number Format Explained (2026)

Last updated: 17 September 2026

Quick Answer: The GSTIN is your permanent 15-digit GST number, while the TRN and ARN are only temporary references from the registration application. You get a TRN after the form's first part, deleted unless you submit within 15 days, and an ARN on submission. Under CGST Rule 10, a GSTIN holds a state code, PAN, entity code and checksum.

The order is always TRN, then ARN, then GSTIN, and only the GSTIN goes on your tax invoices and registration certificate. The GST number format is fixed by the Central Goods and Services Tax (CGST) Rules.

Overview: GSTIN vs ARN vs TRN

	TRN	ARN	GSTIN
Full form	Temporary Reference Number	Application Reference Number	Goods and Services Tax Identification Number
When you get it	After Part A of the form (PAN, mobile and email verified by OTP)	When you submit the full application	When the tax officer approves your registration
How long it lasts	15 days; an unsubmitted draft is then deleted	Temporary; it tracks one application	Permanent unless the registration is cancelled
What you use it for	Logging back in to finish Part B	Tracking your application status	Tax invoices, returns, your registration certificate

What is the difference between GSTIN, ARN and TRN?

The difference is permanence. The GSTIN is your GST registration number, while the TRN and ARN only track an application on its way to one.

The Central Board of Indirect Taxes and Customs (CBIC) agrees: its GST FAQs say an ARN isn't the registration number, because it's "generated only for a temporary period".

When do you get a TRN, and how long is it valid?

You get a TRN when you finish Part A of the GST portal's new registration form. Part A asks for your state, legal name as on PAN, the PAN, and the authorised signatory's mobile and email, each confirmed by OTP.

The GST portal's registration manual for normal taxpayers says if you don't submit within 15 days, the TRN and everything saved against it are purged. Aadhaar authentication, if you choose it, must also be done within 15 days of the TRN.

When do you get an ARN, and what happens next?

You get an ARN when you submit the completed application (Part B), and the receipt reaches your registered email and mobile. If you opted for Aadhaar authentication, the ARN comes only after it's complete.

You then use the ARN to check your GST registration status until the officer approves or rejects it. On approval, your registration ID and password are emailed to you. If you haven't applied yet, Jaagruk Bharat can help you file your GST registration online.

What is the GST number format?

A GST number (GSTIN) has 15 characters in four parts, set by Rule 10 of the CGST Rules: a two-digit state code, a 10-character PAN, a two-character entity code and one checksum character.

Here's each position in a made-up GSTIN, 27ABCDE1234F1Z0:

Position	What it holds	In the example
1–2	State or Union Territory code	27 = Maharashtra
3–12	Permanent Account Number (PAN) of the business or proprietor; for some registrations, the Tax Deduction and Collection Account Number (TAN)	ABCDE1234F
13–14	Entity code	1Z
15	Checksum character	0

What do the first two digits of a GSTIN mean?

The first two digits are the code of the state or Union Territory where the GSTIN is registered. These are the codes on the GST Network's e-invoice master code list:

Code	State / UT	Code	State / UT
01	Jammu and Kashmir	20	Jharkhand
02	Himachal Pradesh	21	Odisha
03	Punjab	22	Chhattisgarh
04	Chandigarh	23	Madhya Pradesh
05	Uttarakhand	24	Gujarat
06	Haryana	25	Daman and Diu
07	Delhi	26	Dadra and Nagar Haveli
08	Rajasthan	27	Maharashtra
09	Uttar Pradesh	29	Karnataka
10	Bihar	30	Goa
11	Sikkim	31	Lakshadweep
12	Arunachal Pradesh	32	Kerala
13	Nagaland	33	Tamil Nadu
14	Manipur	34	Puducherry
15	Mizoram	35	Andaman and Nicobar Islands
16	Tripura	36	Telangana
17	Meghalaya	37	Andhra Pradesh
18	Assam	38	Ladakh
19	West Bengal	97	Other Territory

What do the 13th and 14th characters mean?

Together, the 13th and 14th characters are the entity code, and Rule 10 doesn't give either a separate meaning. It lets one PAN hold more than one GSTIN in the same state, such as a separate registration for a Special Economic Zone unit.

In practice, the 14th character is almost always Z and the 13th is usually 1. In Karnataka's published 2019 list of about 4.5 lakh GSTINs, every one had Z in the 14th place and 98% had 1 in the 13th. So a 2, 3 or a letter in the 13th place isn't an error.

What is the last digit of a GST number?

The 15th character is a checksum, a digit or letter worked out from the first 14 characters. It helps the portal and billing software catch a mistyped GSTIN. A correct checksum only proves the format is possible, though, not that the business is registered.

How can you check if a GST number is valid?

Search it on the GST portal, because a correct format doesn't prove the registration is active. First, three quick checks catch most typing errors on an invoice:

It has exactly 15 characters, with no spaces.
The first two digits match the state on the supplier's address.
Characters 3 to 12 match the supplier's PAN, if you have it.

This step-by-step guide to verifying a GST number walks you through the portal's Search Taxpayer tool.

Your own GSTIN is on your registration certificate, FORM GST REG-06. To have someone confirm a supplier's number for you, use this GSTIN verification service.

What mistakes should you avoid with GST numbers?

Quoting your ARN or TRN as your GST number. Both only track an application; your GST number is the GSTIN.
Leaving the form half-finished. Submit it, with any Aadhaar authentication, within 15 days of getting the TRN.
Using someone else's mobile or email in Part A. The OTPs and your ARN receipt go there, so use the authorised signatory's own.
Paying anyone who promises to "issue" your GSTIN. Only the tax officer approves a registration on the GST portal. A helper, Jaagruk Bharat included, can only help you file.