GSTIN (GST Identification Number)
GSTIN (GST Identification Number)
GSTIN — Goods and Services Tax Identification Number — is the unique 15-digit alphanumeric code assigned to every business, freelancer, or individual registered under India's GST system. It is your tax identity under GST: a permanent identifier that links your invoices, returns, and payments to your PAN and your state of registration.
Once you register for GST on the official portal (gst.gov.in), the government assigns you a GSTIN. This number must appear on every Tax Invoice you raise, every GST return you file, and every correspondence with the GST department. For your B2B clients, your GSTIN on the invoice is what enables them to claim Input Tax Credit (ITC) — making it one of the most commercially significant numbers on any invoice you send.
GSTIN is also commonly called GST Number or GST registration number. All three refer to the same 15-digit code.
Quick reference
| Full form | Goods and Services Tax Identification Number |
| Also called | GST Number, GST registration number |
| Length | Exactly 15 characters (alphanumeric) |
| Issued by | Central Board of Indirect Taxes and Customs (CBIC) via the GST portal |
| Based on | Your PAN — digits 3 to 12 of GSTIN are your PAN |
| Unique to | Each state of registration — same business in two states has two GSTINs |
| Mandatory on | Every Tax Invoice, debit note, credit note, and GST return |
| Buyer needs it to | Claim Input Tax Credit on your invoice |
| Official verification tool | services.gst.gov.in/services/searchtp (free, no login required) |
| Penalty for wrong GSTIN on invoice | ₹25,000 per invoice (Section 122, CGST Act) |
GSTIN format: decoding all 15 digits
Every GSTIN follows a fixed structure. Once you know what each segment means, you can read any GSTIN and extract useful information from it.
Example GSTIN: 29AABCT1234D1Z5
| Position | Characters | What it represents | In this example |
|---|---|---|---|
| 1–2 | 2 digits | State code (Indian Census 2011) | 29 = Karnataka |
| 3–12 | 10 characters | PAN of the business or proprietor | AABCT1234D |
| 13 | 1 digit | Entity number (number of GST registrations under this PAN in this state) | 1 = first registration |
| 14 | 1 letter | Always "Z" by default | Z |
| 15 | 1 character | Check digit (alpha or numeric, auto-generated) | 5 |
Reading the example GSTIN 29AABCT1234D1Z5:
- Registered in Karnataka (state code 29)
- Belongs to a business or individual with PAN AABCT1234D
- This is their first GST registration in Karnataka
- "Z" is a fixed placeholder
- "5" is the system-generated check character
The entity number (digit 13) matters. A business with branches in multiple states has a separate GSTIN per state, all starting with a different state code but sharing the same PAN in positions 3–12. A business with two GST registrations in the same state (e.g. two separate business verticals) would have entity numbers 1 and 2 at digit 13.
Complete GST state code list
The first two digits of every GSTIN are the state code. Knowing these lets you immediately identify which state a supplier is registered in — which determines whether you charge CGST + SGST (same state) or IGST (different state) on your invoice to them.
| Code | State / Union Territory |
|---|---|
| 01 | Jammu & Kashmir |
| 02 | Himachal Pradesh |
| 03 | Punjab |
| 04 | Chandigarh |
| 05 | Uttarakhand |
| 06 | Haryana |
| 07 | Delhi |
| 08 | Rajasthan |
| 09 | Uttar Pradesh |
| 10 | Bihar |
| 11 | Sikkim |
| 12 | Arunachal Pradesh |
| 13 | Nagaland |
| 14 | Manipur |
| 15 | Mizoram |
| 16 | Tripura |
| 17 | Meghalaya |
| 18 | Assam |
| 19 | West Bengal |
| 20 | Jharkhand |
| 21 | Odisha |
| 22 | Chhattisgarh |
| 23 | Madhya Pradesh |
| 24 | Gujarat |
| 26 | Dadra and Nagar Haveli and Daman and Diu |
| 27 | Maharashtra |
| 28 | Andhra Pradesh (new, post-2014 bifurcation) |
| 29 | Karnataka |
| 30 | Goa |
| 31 | Lakshadweep |
| 32 | Kerala |
| 33 | Tamil Nadu |
| 34 | Puducherry |
| 35 | Andaman and Nicobar Islands |
| 36 | Telangana |
| 37 | Andhra Pradesh (old, pre-bifurcation registrations) |
| 38 | Ladakh |
Note: Code 25 (Daman and Diu) was merged into code 26 following the 2020 reorganisation. Code 25 is no longer issued for new registrations.
How to find your own GSTIN
Method 1 — GST portal Log in to your account at gst.gov.in. Your GSTIN is displayed on your dashboard and on your GST Registration Certificate (Form GST REG-06), which you can download from Services → User Services → View/Download Certificate.
Method 2 — Search by PAN Go to services.gst.gov.in → Search Taxpayer → Search by PAN. Enter your PAN number. The portal returns all GSTINs registered under that PAN across all states, along with their status (Active, Cancelled, Suspended).
Method 3 — Check your earlier invoices or bank statements Your GSTIN appears on all Tax Invoices you have raised and on your bank's GST payment challans.
Method 4 — Ask your CA If you registered through a CA or tax practitioner, they will have your GSTIN on file.
How to verify someone else's GSTIN
Before you accept a Tax Invoice from a vendor and claim ITC, always verify their GSTIN. If the GSTIN is fake, cancelled, or mismatched, your ITC claim will be rejected and you may face penalties.
Step 1: Go to services.gst.gov.in/services/searchtp — no login required.
Step 2: Enter the 15-digit GSTIN and complete the CAPTCHA.
Step 3: The portal returns:
- Legal name of the registered business
- Trade name (if different)
- PAN linked to the GSTIN
- State of registration
- Registration date
- Taxpayer type (Regular, Composition, etc.)
- Current status — Active, Cancelled, or Suspended
- Principal place of business address
- Return filing history (GSTR-1 and GSTR-3B month-wise)
What to check:
- Status must be Active — a Cancelled or Suspended GSTIN is invalid for new invoices
- Legal name on the portal must match the supplier name on the invoice
- State code in GSTIN must match the state in the supplier's address
- Return filing history should show regular filings — gaps indicate the supplier may not be depositing tax
GSTIN on your invoice: where it must appear and why
Under Rule 46 of the CGST Rules, the supplier's GSTIN and the recipient's GSTIN (for B2B invoices) are mandatory fields on every Tax Invoice. Their placement and accuracy have real commercial consequences.
Your GSTIN (as the supplier)
Your GSTIN must appear prominently on your invoice — typically in the header, near your name and address. It is your client's proof that you are a registered taxpayer and that the GST you are charging is legitimate. Without it, your invoice is not a valid Tax Invoice and has zero ITC value.
Your client's GSTIN (as the recipient)
For B2B invoices — any invoice raised to another GST-registered business — you must capture and print the client's GSTIN on the invoice. This is what allows your client to claim ITC. When you file your GSTR-1, the invoice is mapped to the client's GSTIN and appears in their GSTR-2B. No client GSTIN on the invoice means the transaction is treated as B2C (business to consumer) — the client loses all ITC.
Practical example: Neha, a digital marketer in Pune, raises an invoice to her client, an e-commerce company in Bengaluru. She enters the company's GSTIN on the invoice. Neha files GSTR-1 and the invoice appears in the company's GSTR-2B. The company claims ₹18,000 ITC on their ₹1,00,000 + 18% GST invoice. If Neha had skipped the client's GSTIN, the ITC would never appear in GSTR-2B and the company would lose ₹18,000 — and likely dispute the invoice.
How to use a client's GSTIN to determine the correct tax type
The first two digits of your client's GSTIN — the state code — tell you immediately whether to charge CGST + SGST or IGST.
| Your state | Client's GSTIN starts with | Tax to charge |
|---|---|---|
| Karnataka (29) | 29 | CGST 9% + SGST 9% |
| Karnataka (29) | 27 (Maharashtra) | IGST 18% |
| Karnataka (29) | 07 (Delhi) | IGST 18% |
| Maharashtra (27) | 27 | CGST 9% + SGST 9% |
| Maharashtra (27) | 33 (Tamil Nadu) | IGST 18% |
Rule: If the first two digits of your client's GSTIN match your own state code — charge CGST + SGST. If they differ — charge IGST.
JetInvoice does this automatically: enter your client's GSTIN and the correct tax type is applied without any manual lookup.
Detecting fake or invalid GSTINs
With GST fraud on the rise, knowing how to spot an invalid GSTIN protects your ITC and keeps you off the GST department's audit list.
Red flags on a vendor invoice
Wrong length. A valid GSTIN is exactly 15 characters. If it is 14 or 16 characters, it is immediately invalid.
PAN mismatch. Characters 3–12 of the GSTIN are the supplier's PAN. Cross-check the PAN shown on the invoice against digits 3–12 of the GSTIN. They must match exactly.
State code mismatch. The first two digits should match the state in the supplier's address on the invoice. A Mumbai supplier with a GSTIN starting with 29 (Karnataka) is a red flag.
Status: Cancelled or Suspended. A supplier whose GSTIN is inactive cannot issue valid Tax Invoices for new transactions. Any invoice issued after the cancellation date is invalid.
No e-invoice QR code (for applicable suppliers). Businesses with annual turnover above ₹5 crore must generate e-invoices with an IRN and QR code. A large supplier without a QR code on their invoice warrants verification.
Name mismatch. The legal name shown on the GST portal for the GSTIN must match the name on the invoice. Fraudsters sometimes copy a valid GSTIN from a legitimate business and use it on their own fake invoices.
What to do if you receive a suspicious invoice
- Verify the GSTIN immediately on services.gst.gov.in
- Do not process payment until verification is complete
- Do not claim ITC on the invoice until verified
- If the GSTIN is confirmed fake, report it to your jurisdictional GST officer or through the GST portal's complaint mechanism
- Retain the invoice as evidence
ITC on a fake invoice is dangerous. If you claim ITC based on an invoice with a fake or invalid GSTIN — even if you were unaware — the tax department can reverse your ITC, demand the tax with 18% interest, and impose penalties. Always verify before claiming.
GSTIN vs GST Number vs UIN: clearing up the confusion
| Term | What it is |
|---|---|
| GSTIN | The standard 15-digit tax ID for all regular GST-registered taxpayers (businesses, freelancers, companies) |
| GST Number | Informal name for GSTIN — refers to the same 15-digit code |
| UIN (Unique Identification Number) | A 15-digit number assigned specifically to foreign diplomatic missions, embassies, and UN bodies — not the same as GSTIN |
| TAN | Tax Deduction and Collection Account Number — a 10-digit number for TDS purposes under the Income Tax Act, completely separate from GSTIN |
| PAN | Permanent Account Number — 10 characters, sits inside GSTIN at positions 3–12, used for income tax |
Common GSTIN mistakes Indian businesses make
Printing GSTIN in the wrong place on the invoice. Many freelancers put their GSTIN in a small footer or an afterthought section. It should be clearly visible in the invoice header near your name and address — the first thing the buyer's accounts team looks for.
Forgetting the client's GSTIN on B2B invoices. Some freelancers raise invoices without asking for the client's GSTIN. Every B2B invoice must carry the recipient's GSTIN or the client loses ITC. Always collect GSTIN before raising the invoice — not after.
Entering GSTIN with spaces or hyphens. GSTIN is a continuous 15-character string with no spaces, dots, or hyphens. 29-AABCT1234D-1Z5 or 29 AABCT1234D 1Z5 are incorrectly formatted. Write it as 29AABCT1234D1Z5.
Using an old GSTIN after cancellation. If you cancelled your GST registration and later re-registered, you receive a new GSTIN. Using a cancelled GSTIN on new invoices is an offence under the GST Act.
Not verifying vendor GSTINs. Many businesses trust the GSTIN their vendor puts on the invoice without verifying. A one-minute check on the GST portal can prevent costly ITC reversals months later during return reconciliation.
Using the wrong GSTIN when operating in multiple states. If your business has branches in Maharashtra and Karnataka, you have two separate GSTINs — one starting with 27 and one starting with 29. Invoices from the Maharashtra branch must use the Maharashtra GSTIN, not the Karnataka one. Using the wrong GSTIN for a transaction leads to incorrect ITC flow and mismatched returns.
Frequently asked questions
What is GSTIN?
GSTIN stands for Goods and Services Tax Identification Number. It is a unique 15-digit alphanumeric code issued to every GST-registered business or individual in India. The GSTIN encodes the state of registration (first 2 digits), the registrant's PAN (next 10 characters), and system-generated identifiers. It must appear on every Tax Invoice and is required for claiming Input Tax Credit.
What is the full form of GSTIN?
GSTIN stands for Goods and Services Tax Identification Number.
How many digits is a GSTIN?
A GSTIN is exactly 15 characters — a mix of characters and letters (alphanumeric). It starts with a 2-digit state code, followed by the 10-character PAN of the business, and ends with 3 system-assigned characters.
How do I find my GSTIN?
Log in to your GST account at gst.gov.in to find your GSTIN on your dashboard or GST Registration Certificate. You can also search by your PAN at services.gst.gov.in → Search Taxpayer → Search by PAN without logging in.
How do I verify a GSTIN?
Go to services.gst.gov.in/services/searchtp, enter the 15-digit GSTIN, and complete the CAPTCHA. No login is required. The portal shows the business's legal name, registration status (Active/Cancelled/Suspended), address, and return filing history. Always verify a vendor's GSTIN before claiming ITC on their invoice.
Can two businesses have the same GSTIN?
No. A GSTIN is unique to each registered entity in each state. However, the same PAN can have multiple GSTINs — one per state where the business is registered. Each GSTIN will have the same PAN in positions 3–12 but will differ in the state code (positions 1–2) and possibly the entity number (position 13).
What happens if the wrong GSTIN is on my invoice?
A wrong GSTIN on an invoice can result in your client being unable to claim ITC, a ₹25,000 penalty per invoice under Section 122 of the CGST Act, and potential audit triggers for both you and your client. If you discover an error after issuing the invoice, issue a credit note for the incorrect invoice and raise a fresh corrected invoice.
Is GSTIN the same as GST number?
Yes. GSTIN and GST number refer to the same 15-digit code. GST number is the informal term commonly used in everyday conversation; GSTIN is the official term used in the GST Act, rules, and government communications.
Related terms
GST · GST Registration · GST Rate · Tax Invoice · Input Tax Credit · CGST · SGST · IGST · Place of Supply · GSTR-1 · E-Invoice
JetInvoice auto-fills buyer details from GSTIN
Enter your client's GSTIN on JetInvoice and it instantly fetches their registered business name, address, and state — no manual typing. It also detects whether the transaction is intra-state or inter-state and applies the correct CGST + SGST or IGST automatically. Get a fully compliant Tax Invoice PDF ready to share in under 2 minutes.