GST Number Validator
Validate Indian GSTIN (GST Identification Numbers) against all structural rules — 15-character format, state code, embedded PAN segment, entity type, and mod-36 checksum digit. Single or bulk validation. Runs entirely in your browser.
15 characters — auto uppercased
GSTIN structure (15 characters)
A GSTIN is a 15-character alphanumeric identifier assigned to every GST-registered taxpayer in India. First 2 digits = state code, chars 3–12 = PAN, char 13 = entity registration number (1–9), char 14 = default Z, char 15 = mod-36 checksum.
GSTIN structure (15 characters)
Validation checks performed
- 1.Length — Exactly 15 characters (alphanumeric, uppercase)
- 2.Characters — Only digits (0–9) and uppercase letters (A–Z)
- 3.State code — First 2 digits must match a valid Indian state/UT code
- 4.PAN segment — Characters 3–12 must match PAN format: 5 letters + 4 digits + 1 letter
- 5.Entity number — Character 13 must be 1–9
- 6.Z placeholder — Character 14 must be the letter Z
- 7.Checksum — Character 15 must match the mod-36 checksum of characters 1–14
Frequently asked questions
What is the difference between GST registration and GSTIN?
GST registration is the process of enrolling a business with the GST system. Upon successful registration, the government assigns a GSTIN — the unique 15-character identification number. GSTIN is the output of GST registration, used for all tax filings, invoices, and GST compliance.
Does a valid GSTIN format mean the business is GST-registered?
No. This tool validates the format and structure of a GSTIN — state code, PAN segment, entity number, Z placeholder, and checksum. A structurally valid GSTIN does not guarantee the business is currently registered. To verify active GST registration, use the official GST portal (gst.gov.in) search.
What does "invalid checksum" mean in a GSTIN?
The 15th character of a GSTIN is a verification digit calculated from the first 14 characters using a mod-36 algorithm. If the checksum digit does not match the expected value, the GSTIN has been entered incorrectly or is fabricated. A valid format with a wrong checksum is not a genuine GSTIN.
How do I look up the state from a GSTIN?
The first two digits of a GSTIN are the state code. For example, 07 = Delhi, 27 = Maharashtra, 29 = Karnataka, 33 = Tamil Nadu, 36 = Telangana. This validator decodes the state name from the state code for every valid GSTIN.