From ARN to GSTIN: Tracking a Registration to Its Number

A GSTIN search by ARN only works one way: the ARN tracks the application, and once that application is approved the portal shows you the GSTIN it produced. You cannot feed someone else's Application Reference Number into a public lookup and get their GST number back. If you are the applicant, tracking the ARN on the GST portal is how you find out when your GSTIN has been allotted; if you are a buyer who has been handed an ARN by a new vendor, the honest answer is that there is nothing to verify yet.

What an ARN actually is

When you submit an application on the GST portal — a new registration in Form GST REG-01, an amendment, a cancellation, a refund claim — the portal acknowledges the submission and issues an Application Reference Number. For a new registration the acknowledgement comes as Form GST REG-02, and it is emailed and SMSed to the contact details on the application.

The important thing to understand is that an ARN is a docket number. It says "an application of this type was received on this date and is now in the queue". It carries no tax identity: it does not appear in anyone's GSTR-1, it cannot be quoted on a tax invoice, and it stops being useful the moment the application reaches a final state.

Two other reference numbers get confused with it constantly, so it is worth pinning down the difference before going further.

If you have not started the application yet, our walkthrough of the online GST registration process covers what goes into Part A and Part B before any of this becomes relevant.

The ARN format, and why you should not parse it

An ARN is 15 characters long and alphanumeric — the same length as a GSTIN, which is precisely why it ends up pasted into the wrong field so often. The pattern that is commonly documented is two leading letters, the two-digit state code, the month and year the application was filed, a six-digit system-generated serial and a final check character, giving something that looks like AA0709260000123X in shape if not in substance.

Treat that as a description of what you will usually see, not as a validation rule. The portal is the authority on what a valid ARN looks like, the composition has changed over the years, and ARNs for amendments and refunds do not necessarily follow the same convention as ARNs for new registrations. If you are writing code, validate an ARN as "15 alphanumeric characters" and let the portal reject anything genuinely malformed.

Tracking an ARN on the GST portal

Status tracking for a registration ARN is a pre-login service, so you do not need credentials — which is useful, because during a first-time registration you do not have any yet.

1. Go to gst.gov.in and open Services → Registration → Track Application Status.
2. Choose Registration as the module.
3. Search by ARN and paste the number in exactly as issued — no spaces, and watch for a trailing space picked up from a copy-paste out of an email.
4. Complete the captcha and submit. The portal returns the current stage of the application, and once the application is decided, the outcome.

The same page also lets you search by submission period if the ARN has genuinely been lost, and post-login there is an equivalent under Services → Track Application Status that covers other module types such as refunds. For a registration you are chasing on behalf of a client, the pre-login route is usually the fastest.

What each application status means

The status strings the portal returns are more informative than they look. The distinction that matters most is between a status where the ball is in the officer's court and one where it is in yours — a registration that sits at "Pending for Clarification" for three weeks is not a slow department, it is an unanswered notice.

When the GSTIN is issued and the certificate appears

The GSTIN is generated at the moment the application is approved — not when it is submitted, and not when site verification is completed. On approval the portal displays the GSTIN against the application, and the number is sent to the email address and mobile number on the application together with a temporary username and password for the first login. On that first login you set your own credentials, and only then can you download the registration certificate.

The certificate itself is Form GST REG-06, available under Services → User Services → View/Download Certificates. It carries the GSTIN, the legal and trade name, the constitution of business, the principal place of business and — the field people most often overlook — the effective date of registration.

That effective date is not always the approval date. Under Rule 10 of the CGST Rules, where the application is filed within the prescribed window after the person becomes liable to register, the registration is effective from the date liability arose rather than from the date it was granted. That backdating is what makes the invoicing question below solvable. The exact windows and their conditions are the sort of thing worth reading in the current rules on cbic-gst.gov.in rather than taking on trust from a summary.

How long the whole thing takes depends chiefly on whether Aadhaar authentication succeeded and whether the application was flagged as risky. A clean, authenticated application runs on a short statutory clock under Rule 9; one that requires physical verification or a clarification runs considerably longer, and the clock effectively restarts when your REG-04 reply is filed. Those day counts have been revised more than once, so check the current text of Rule 9 rather than a number quoted second-hand.

Why an ARN is not a substitute for a GSTIN on an invoice

This is where businesses get themselves into trouble in the gap between applying and being approved. The rule is blunt: section 32 of the CGST Act says a person who is not a registered person shall not collect any amount by way of tax. Until the GSTIN exists, you are not registered, so you cannot charge GST — and quoting an ARN on the invoice does not change that.

From the buyer's side it fails for a different reason. Input tax credit runs off supplier-reported invoice data keyed to a GSTIN, which flows into the recipient's GSTR-2B and the Invoice Management System. An invoice with an ARN in the GSTIN field cannot be reported by the supplier and will never appear against you, so any tax "charged" on it is simply a cost you have absorbed.

The workable sequence during the waiting period is:

• Bill without GST. Raise a plain commercial invoice for the taxable value only. Do not add a GST line, and do not label the document a tax invoice.
• Tell the customer why. A one-line note saying registration is pending under ARN x, with tax to be recovered by revised invoice on approval, avoids a dispute later.
• Issue revised invoices once the certificate arrives. Section 31(3)(a) of the CGST Act lets a newly registered person issue revised invoices, within one month of the date the registration certificate is issued, against invoices already raised for the period between the effective date of registration and the date of the certificate. That is the mechanism that lets you go back and charge the tax properly — and it is why the effective date on Form GST REG-06 matters.
• Do not let it into your master data. On the receiving side, an AP team that accepts an ARN into a GSTIN field has created a record that will fail every subsequent vendor verification run. Park it in a separate field, flag the vendor as registration-pending, and block GST postings until the real number arrives.

Verifying the new GSTIN through an API

Once the status flips to Approved and you have the number, the work is not quite done. Verify it — against the GST database, not against the email it arrived in. For your own registration this confirms the legal name and state code came through as you filed them; for a vendor's newly issued GSTIN it is the only way to know the number they typed into their onboarding form is real.

A single GET call is enough:

curl -s https://gstinapi.com/api/get-taxpayer-info/27AAACR5055K1Z7 \
  -H "x-api-key: YOUR_API_KEY"

The practical pattern for a registration you are waiting on is to poll the number the moment you have it and keep the result. In Python, that is a dozen lines:

import requests

API_KEY = "YOUR_API_KEY"


def verify(gstin: str) -> dict:
    response = requests.get(
        f"https://gstinapi.com/api/get-taxpayer-info/{gstin}",
        headers={"x-api-key": API_KEY},
        timeout=10,
    )
    response.raise_for_status()
    return response.json()


record = verify("27AAACR5055K1Z7")
print(record)

What to check in the response, in order of how often it catches something:

• Legal name. It must match the PAN-holder's name on the registration, not the trade name on the letterhead. A mismatch here on a vendor GSTIN is the classic sign that someone has pasted a number belonging to a different entity.
• Status. A brand-new registration should come back active. If it comes back suspended or cancelled on day one, you have almost certainly been given an old number rather than the new one — see what a suspended status actually means.
• Registration date. For a freshly granted GSTIN this should line up with the effective date printed on Form GST REG-06. If it does not, read the certificate again before you start invoicing from the earlier date.
• State code. The first two digits should match the state of the principal place of business on the application; our GST state code list maps them.

Newly granted registrations sometimes take a little while to propagate into public search data, so a lookup that returns nothing within the first day or two of approval is worth retrying before you treat it as a red flag. If you want the full request and response shape, the GST number verification API walkthrough covers it field by field.

Can you look up someone else's GSTIN from their ARN?

No, and it is worth being clear about why, because the question comes up in AP teams constantly. The ARN tracking service returns a processing status to whoever holds the number; it is not a directory. There is no public endpoint that maps an ARN to a GSTIN, and no verification API — ours included — can do it either, because until the application is approved there is no GSTIN in the database to return.

If a supplier has given you an ARN, your options are:

• Ask them to send the GSTIN once granted, ideally with the Form GST REG-06 PDF attached, and set a diary reminder rather than waiting to be told.
• Search by PAN. The GST portal's Search Taxpayer → Search by PAN service lists the GSTINs registered against a PAN across states. If you already hold the vendor's PAN, this will show the new registration as soon as it exists — and will also show you any other registrations they hold. Our GST number search tool covers the same ground for a known GSTIN.
• Transact without GST in the meantime. Accept an invoice with no tax charged, and expect a revised invoice once they are registered. Do not pay a GST component to an unregistered supplier on the strength of an ARN.

The last point deserves emphasis. "GST registration in process, here's the ARN" is a plausible-sounding line that has been used to extract tax amounts that were never going to be remitted. Treating a pending registration as a reason to withhold the tax component, rather than a reason to pay it on faith, costs you nothing and closes the exposure entirely.

Frequently asked questions