GST Number Validator — Check & Verify GSTIN Free Online
Validate any GSTIN instantly — check the structure, decode state code, entity type, and verify the check digit. Free GSTIN verification tool for India.
Format: 2-digit state code + 10-char PAN + registration number + Z + check digit
How to Validate a GSTIN Online
- 1Enter the 15-character GSTIN in the input field. The tool auto-capitalises your input.
- 2Click "Validate" or press Enter.
- 3View the result — Valid (green) or Invalid (red) with the specific error reason.
- 4For valid GSTINs, see the full decoded breakdown: state, PAN, entity type, registration number, and verified check digit.
- 5Use the "Try sample" buttons to see example results for different entity types.
GSTIN Format & Validation Method
A GSTIN (GST Identification Number) is always exactly 15 characters. This tool performs three levels of validation:
Level 1 — Format
- • Exactly 15 characters
- • Positions 1–2: digits only
- • Positions 3–7: uppercase letters
- • Positions 8–11: digits only
- • Position 12: uppercase letter
- • Position 13: 1–9 or A–Z
- • Position 14: always Z
- • Position 15: digit or A–Z
Level 2 — State Code
- • Positions 1–2 must match a known state/UT code (01–38)
- • Decodes state name and whether it's a Union Territory
- • Union Territories use UTGST instead of SGST
Level 3 — Check Digit
- • Each character → numeric value (0–9, A=10, …, Z=35)
- • Alternate weights of 1 and 2 applied
- • Products ≥36 split: quotient + remainder
- • Check = (36 − sum mod 36) mod 36
- • Catches single-character errors and most transpositions
GSTIN Structure — 15 Positions
| Positions | Characters | Meaning |
|---|---|---|
| 1–2 | NN | State / UT code (01–38) |
| 3–7 | AAAAA | First 5 chars of PAN (uppercase letters) |
| 8–11 | 9999 | PAN entity number (digits) |
| 12 | A | PAN check character |
| 13 | 1–9/A–Z | Registration number (1 = first registration in state) |
| 14 | Z | Always Z (reserved) |
| 15 | N/A | Check digit (calculated) |
GSTIN Decoding Example with Real Numbers
GSTIN: 27AAPFU0939F1ZV
| Position | Characters | Decoded Meaning |
|---|---|---|
| 27 | State code 27 | Maharashtra |
| AAPFU0939F | PAN | AAPFU0939F |
| F (PAN[3]) | Entity type | Firm / LLP / Partnership |
| 1 | Registration number | First registration in Maharashtra |
| Z | Reserved | Always Z |
| V | Check digit | ✓ Verified |
Common GSTIN Mistakes to Avoid
Confusing GSTIN with PAN
Your PAN is 10 characters (e.g., AAPFU0939F). Your GSTIN is 15 characters and includes your PAN embedded within it. You cannot use a PAN in place of a GSTIN on invoices.
Adding spaces or dashes
A GSTIN has no spaces, dashes, or separators. It is exactly 15 contiguous alphanumeric characters. Adding formatting characters will fail validation.
Confusing O (letter) with 0 (zero)
GSTINs use digits 0–9 and uppercase letters A–Z. Letters O and I can be confused with digits 0 and 1. Carefully check digits 0–9 against letters when reading from printed documents.
Assuming a valid structure means an active registration
This tool validates the GSTIN structure and check digit. A structurally valid GSTIN could still be cancelled, suspended, or belong to a different business. Always verify active status on gst.gov.in before accepting vendor invoices.
Frequently Asked Questions — GSTIN Validation
Q: What is a GSTIN and how many characters does it have?
GSTIN (GST Identification Number) is a 15-character alphanumeric code assigned to every GST-registered taxpayer in India. It is structured as: 2-digit state code + 10-character PAN + 1-digit registration number + the letter Z + 1 check digit. For example: 27AAPFU0939F1ZV. Every registered business, firm, and individual has a unique GSTIN.
Q: How to validate a GSTIN online?
To validate a GSTIN: (1) Check it is exactly 15 characters with no spaces or special characters. (2) The first 2 digits must be a valid state code (01–38). (3) Characters 3–12 must match the taxpayer's PAN. (4) Character 14 must always be the letter Z. (5) The 15th character (check digit) is calculated from the other 14 using the GSTN algorithm. This tool performs all these checks instantly and decodes the embedded information.
Q: What does each part of a GSTIN mean?
A GSTIN has 5 parts: (1) State code (positions 1–2): identifies the state of registration. (2) PAN (positions 3–12): the taxpayer's 10-character Permanent Account Number. (3) Entity number (position 13): 1 for first registration, 2 for second, etc. — used when a business has multiple GST registrations in the same state. (4) The letter Z (position 14): always Z. (5) Check digit (position 15): a calculated character used to verify the GSTIN was not tampered with.
Q: What are the state codes in GSTIN?
The first two digits of a GSTIN identify the state or union territory. Common codes: 07 — Delhi, 09 — Uttar Pradesh, 19 — West Bengal, 22 — Chhattisgarh, 24 — Gujarat, 27 — Maharashtra, 29 — Karnataka, 32 — Kerala, 33 — Tamil Nadu, 36 — Telangana, 37 — Andhra Pradesh. Union territories have codes like 04 (Chandigarh), 07 (Delhi), 34 (Puducherry), 38 (Ladakh).
Q: What is the difference between GSTIN, GSTN, and UIN?
GSTIN is the unique 15-character number assigned to each registered taxpayer. GSTN (Goods and Services Tax Network) is the technology company that runs the GST portal (gst.gov.in). UIN (Unique Identity Number) is a separate 15-character code assigned to certain entities like embassies, consulates, and UN agencies — they do not pay GST but can claim refunds on purchases made for official use.
Q: Can I validate a GSTIN without internet access?
Structural validation — checking the format, state code, and check digit — can be done offline because the check digit is calculated from the GSTIN itself. This tool does exactly that. However, verifying whether a GSTIN is currently active (not cancelled or suspended) requires checking the official GST portal (gst.gov.in) or via the GST API, which needs internet access.
Q: What entity types can be found in a GSTIN?
The 4th character of the embedded PAN (position 5 of the GSTIN) indicates the entity type: P — Individual / Sole Proprietor, C — Private or Public Company, H — Hindu Undivided Family (HUF), F — Firm, LLP, or Partnership, A — Association of Persons (AOP), T — Trust, B — Body of Individuals (BOI), L — Local Authority, J — Artificial Juridical Person, G — Government Entity.
Q: Why does a GSTIN have the letter Z as position 14?
Position 14 is always the letter Z in current GSTINs. This is reserved by the GSTN system and was originally intended to allow for future expansion of the numbering system. All GSTINs issued today have Z at this position. A GSTIN with any other character at position 14 is structurally invalid.
Q: What is a GSTIN check digit and how is it calculated?
The check digit is the 15th character of a GSTIN. It is calculated from the preceding 14 characters using a weighted algorithm where each character is assigned a numeric value (0–9 → 0–9, A–Z → 10–35), multiplied by alternating weights of 1 and 2, and summed. The check digit ensures that any single character error or transposition in the GSTIN can be detected. If the check digit doesn't match, the GSTIN has been altered or mistyped.
Q: How many GSTINs can a business have?
A business can have multiple GSTINs — one for each state or union territory where it operates. Each state registration gets a separate GSTIN with the same PAN but different state code (first 2 digits). Within the same state, if a business has multiple business verticals, the entity number at position 13 increments (1, 2, 3, ..., A, B, ...). A large national business may have 30+ GSTINs.
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