When you apply for GST registration on the government portal, the process does not happen in a single sitting. The portal divides it into two parts. After you complete Part A and verify your OTP, you receive a temporary reference number in GST – a 15-digit code that acts as your saved progress. You use this number to return to the portal and finish the rest of the application.
If you have started GST registration and are not sure what to do with the TRN you received, or if you want to understand the full process before you begin, this guide covers everything you need to know.
What is a temporary reference number in GST?
A temporary reference number (TRN) is a 15-digit alphanumeric code generated by the GST portal after you successfully complete Part A of the GST registration application (Form GST REG-01). It is not your GSTIN. It is not an approval. It is simply a session token that lets you pause and resume your registration.
Think of it as a bookmark. Part A captures your basic details – your PAN, mobile number, email address, and business name. Once verified, the portal issues the TRN and waits for you to come back and complete Part B with your full business details, documents, and address information.
The TRN is sent to you via SMS and email at the time of generation. It also appears on-screen immediately after OTP verification in Part A.
When is a TRN generated?
The TRN is generated automatically at the end of Part A verification. This happens when:
- You visit gst.gov.in and click Services > Registration > New Registration
- You select your taxpayer type (regular, casual, non-resident, etc.)
- You enter your PAN, legal business name, state, email ID, and mobile number
- You verify both the email OTP and the mobile OTP (each valid for 10 minutes)
Once all OTPs are successfully verified, the portal generates and displays the TRN. You will also receive it on your registered email and phone.
How to use TRN to complete GST registration
After you have your TRN, here is how to use it to finish the registration process (Part B):
- Go to gst.gov.in and click Services > Registration > New Registration
- On the registration page, select “Temporary Reference Number (TRN)” instead of “New Registration”
- Enter your TRN and complete the CAPTCHA
- Verify the OTP sent to your registered mobile and email (these are different from the Part A OTPs)
- You will land on the Part B dashboard, which contains several tabs: Business Details, Promoter/Partner, Authorised Signatory, Authorised Representative, Principal Place of Business, Additional Places of Business, Goods and Services, Bank Accounts, State Specific Information, Aadhaar Authentication
- Fill in all tabs and upload the required documents
- Submit using OTP-based e-verification, EVC, or DSC
Once submitted, the portal processes your application and issues an Application Reference Number (ARN). You use the ARN to track your registration status going forward.
TRN validity: how long does it last?
A TRN is valid for 15 days from the date it is generated. If you do not complete and submit Part B within those 15 days, the TRN and all the information you filled in under it are permanently deleted. You will need to start the entire process from scratch – generating a new TRN by re-filling Part A.
There is no way to extend or reactivate an expired TRN. The 15-day window is fixed.
Additionally, Aadhaar authentication must also be completed within this 15-day window. If it is not completed in time, no ARN is generated.
Key deadline to remember
| Task | Deadline |
|---|---|
| Complete Part B and submit application | Within 15 days of TRN generation |
| Complete Aadhaar authentication | Within 15 days of TRN generation |
| Biometric verification at GSK (if applicable) | Within 15 days of TRN generation |
TRN vs ARN: what is the difference?
A lot of first-time applicants confuse TRN with ARN. They serve completely different purposes at different stages of the registration process.
| Aspect | TRN (temporary reference number) | ARN (application reference number) |
|---|---|---|
| Generated after | Part A submission and OTP verification | Complete application (Part B) submission |
| Purpose | Resume incomplete application | Track submitted application status |
| Validity | 15 days | Until GSTIN is issued or rejected |
| Format | 15-digit alphanumeric | 15-digit (includes state code and date) |
| Use after expiry | Cannot be used; start over | Does not expire |
Once you receive your ARN, you can check your GST application status at any point under Services > Registration > Track Application Status on the GST portal.
Documents you need to complete Part B
When you log back in using your TRN to fill Part B, keep these documents ready. Missing documents are one of the most common reasons registrations get stuck or notices are issued.
- PAN card of the business or proprietor
- Aadhaar card of the authorised signatory (for e-KYC, now mandatory)
- Proof of principal place of business – rent agreement, NOC, electricity bill, or ownership documents
- Bank account details – cancelled cheque or bank statement
- Photograph of the authorised signatory
- Digital signature certificate (DSC) for companies and LLPs
- Board resolution or partnership deed for companies and firms
The address proof documents you submit for your principal place of business are particularly important. The GST officer verifies the address during application processing. If the documents are inconsistent or the address cannot be verified, your application will receive a notice or get rejected. See this detailed guide on address proof for GST registration to make sure you submit the right documents.
What happens after the TRN expires?
If your TRN expires before you complete Part B:
- All data entered under that TRN is deleted from the GST portal
- You cannot recover the information
- You must restart from Part A: visit gst.gov.in, fill in your basic details again, verify OTPs, and generate a new TRN
This is not a penalty situation – you can restart as many times as you need. But it does mean your registration gets delayed. If you are applying for GST ahead of a business deadline (like starting to sell on an e-commerce platform), factor in the 15-day window when you begin the process.
Who needs a TRN?
Anyone who initiates a new GST registration on the portal receives a TRN. This includes:
- Sole proprietors and individual businesses
- Private limited companies and LLPs
- Partnerships and HUFs
- Trusts and NGOs
- E-commerce operators and sellers
- Casual taxable persons and non-resident taxable persons (NRTPs get a limited TRN valid for 90 days)
- Freelancers registering voluntarily
There is no separate process to request a TRN – it is issued automatically when you complete Part A successfully.
Common mistakes that waste your TRN window
Most people who fail to complete registration within 15 days do so for avoidable reasons. Watch out for these:
- Not saving the TRN immediately. Write it down or take a screenshot. If you lose it and cannot find the email or SMS, you will need to use the “Search Temporary ID” feature on the GST portal or restart.
- Delaying document collection. The most time-consuming part of Part B is gathering address proof, bank documents, and DSC. Start this before generating the TRN, not after.
- Incorrect business address. If the address on your documents does not match what you enter in Part B, the application will be flagged. Use a consistent, verifiable address across all documents.
- Skipping Aadhaar authentication. Since October 2024, Aadhaar e-KYC is mandatory during the TRN validity period. Missing this step means no ARN is generated even after full submission.
- Documents above 100 KB. The GST portal has file size limits. Documents larger than 100 KB will not upload. Compress your files before uploading.
- PAN-Aadhaar mismatch. If your name on PAN does not match Aadhaar exactly, the verification step fails. Correct this before applying.
Using a virtual office address for GST registration
One of the most common reasons businesses delay completing Part B – or receive notices after submission – is the principal place of business address. If you are a startup, a freelancer, a remote business, or expanding to a new city, you may not have a physical commercial office. In that case, using a home address creates compliance issues, and a friend’s address creates legal exposure.
A virtual office solves this cleanly. It gives you a legitimate, commercially registered address in a prime business location – with the supporting compliance documents (rent agreement, NOC, utility bill) that the GST portal requires for address proof. These documents are issued in your company’s name, making your registration straightforward.
This is particularly relevant for businesses registering at an Additional Place of Business (APOB), e-commerce sellers who need a registered address in multiple states, or anyone who needs GST registration but does not operate from a physical office. You can read more about this in our guide on GST registration at PPOB and APOB address.
myHQ Virtual Office provides GST-ready addresses across 25+ Indian cities. You get a prestigious commercial address, a proper rent agreement, NOC, and utility bill – all accepted by the GST department for registration. The process is 100% digital, documents are delivered within 72 hours, and there is a 100% acceptance guarantee. Plans start at ₹999/month.
For a complete overview of the GST registration process in India, including documents, fees, and timeline, see our full guide.
Frequently asked questions
Can I use the same TRN for multiple registrations?
No. Each new GST registration application generates a unique TRN. If you need to register in multiple states, each application has its own separate TRN.
Where can I find my TRN if I have lost it?
Check the email and SMS sent to your registered contact at the time of Part A submission. Alternatively, visit the “Search Temporary ID” page on the GST portal (Services > Registration > Search Temporary ID) and enter your PAN to retrieve it.
Is TRN the same as GSTIN?
No. TRN is a temporary code used only to complete an in-progress registration. GSTIN is your permanent 15-digit tax identification number issued after the registration is approved.
Can I update my details after generating a TRN?
Yes. All information entered in Part B remains editable until you submit the final application. Once submitted, modifications depend on the type of field and may require a formal amendment request.
What is the difference between TRN and ARN in GST?
TRN is generated after Part A and is used to complete the application. ARN is generated after Part B is submitted and is used to track the application status with the GST authorities.
Does the TRN expire on weekends?
Yes. The 15-day validity counts calendar days, not business days. There are no extensions for weekends or public holidays.
What is an LTRN?
LTRN stands for Limited Temporary Reference Number. It is issued to casual taxable persons and non-resident taxable persons. Unlike the standard 15-day TRN, an LTRN is valid for 90 days and is linked to the estimated period of business activity.
