GSTIN full form: Goods and Services Tax Identification Number. It is the unique 15-character identity assigned to every business registered under GST in India — the number that appears on every tax invoice, every return, and every registration certificate.
What exactly is a GSTIN?
When India moved to the Goods and Services Tax regime in July 2017, it replaced a patchwork of indirect-tax registrations — VAT TINs issued by individual states, service tax numbers issued by the Centre, excise registrations — with a single identifier per registration: the GSTIN. It is issued by the tax administration through the GST Network (GSTN) when a business registers, and it is state-specific: a business gets one GSTIN for each state or Union Territory in which it registers, all built on the same PAN.
Three properties make the GSTIN unusually useful:
- It is public. Anyone can verify anyone’s GSTIN. The system is designed for counterparties to check each other, because the input tax credit chain only works if fake registrations can be spotted.
- It is structured. The 15 characters are not random — they encode the state, the PAN and a registration counter, and end in a check digit. You can read a surprising amount from the number alone.
- It is self-validating. The final character is computed from the first fourteen, so most typos and many crude fakes can be detected mathematically, before any database is consulted.
The 15 characters, decoded
Using the example 27AAPFU0939F1ZV:
| Position | Example | What it encodes |
|---|---|---|
| 1–2 | 27 |
State code of the registration — 27 is Maharashtra. Every state and UT has a two-digit code; the full set is on the GST state code list. |
| 3–12 | AAPFU0939F |
The registrant’s PAN, unchanged. The fourth character of the PAN even reveals the entity type — F here means a partnership firm. |
| 13 | 1 |
Entity code: the serial number of this PAN’s registrations within the state, running 1–9 then A–Z. |
| 14 | Z |
A default character, currently always Z, kept in reserve. |
| 15 | V |
The check digit, calculated from characters 1–14. |
A deeper character-by-character walkthrough, including how the check digit works and the mistakes people make transcribing GSTINs, is in the GST number format guide.
GSTIN vs PAN vs the old TIN
These three get conflated constantly. The PAN (10 characters) identifies a taxpayer for income tax — one per entity, nationwide. The GSTIN (15 characters) identifies a GST registration — potentially several per entity, one per state, each containing the PAN inside it. The TIN was the old 11-digit VAT-era number issued by state commercial tax departments; it is obsolete and any current invoice showing only a TIN should raise questions. If you have a PAN and want to see the registrations built on it, use GST search by PAN.
Who must have a GSTIN?
Broadly: businesses whose aggregate turnover crosses the registration threshold (₹40 lakh for most goods suppliers, ₹20 lakh for services, with lower limits in special category states), plus several categories that must register regardless of turnover — inter-state suppliers of goods, e-commerce sellers on platforms that collect tax at source, casual and non-resident taxable persons, and those liable under reverse charge. Voluntary registration is also allowed and is common among small B2B suppliers whose customers want the input tax credit. The process, documents and timelines are covered in how to get a GST number.
Why you will be asked for a GSTIN — and why you should ask for one
On a tax invoice, the supplier’s GSTIN is what lets the buyer claim input tax credit; the buyer’s GSTIN is what routes that credit to the right taxpayer. Get either wrong and the credit chain breaks. This is why accounts teams verify a new vendor’s GSTIN before the first payment, and why a B2B customer will insist their GSTIN appears correctly on your invoice. A quick GST number check tells you whether any GSTIN is valid and currently active — and the GST Search homepage lets you look one up by number, PAN or name in a single box. हिंदी में समझना चाहते हैं? पढ़ें: GST नंबर क्या होता है.
GSTIN FAQs
What is the full form of GSTIN?
Goods and Services Tax Identification Number — the 15-character identifier assigned to every GST-registered business in India, unique to each state-level registration.
Are GSTIN and GST number the same thing?
Yes. “GST number”, “GSTIN” and “GST registration number” all refer to the same 15-character identifier. “GSTN”, however, is different — that is the GST Network, the organisation running the technology backbone.
Can one business have more than one GSTIN?
Yes — one per state or UT of operation, and sometimes more than one within a state (for example an SEZ unit registered separately). All of them share the same PAN in characters 3–12, so the PAN search mentioned above lists them together.
Is a GSTIN confidential?
No — it is intentionally public information, printed on invoices and signboards and verifiable by anyone. What stays private is the taxpayer’s filing data and financials, not the registration identity itself.
How do I check whether a GSTIN is genuine?
Search it on the GST Search homepage linked above. The tool validates the format and check digit, then returns the registration’s legal name, trade name, state and live status from GSTN records. If the status is anything other than Active, the GST number check guide explains what each status means and what to do.
Does a GSTIN expire?
A regular taxpayer’s GSTIN has no expiry date — it remains valid until cancelled (voluntarily or by the department). Registrations for casual and non-resident taxable persons are the exception: those are granted for a limited period and must be extended.