🔍 Format & Checksum Validator
GSTIN Validator & Decoder
Paste any 15-character GSTIN to instantly verify its format, decode the embedded state, PAN, and entity type — all without any API call or internet dependency.
Enter GSTIN to Validate
Validation runs automatically as you type.
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Enter a GSTIN above to validate
Results appear instantly — no button to click
What does a GSTIN contain?
27
State Code
AAAPL1234C
PAN (10 chars)
1
Entity #
Z
Default
V
Check Digit
Every GSTIN encodes the taxpayer's state, their PAN, a registration count for that PAN, a fixed "Z" placeholder, and a computed check digit. Our validator decodes all five segments.
Frequently Asked Questions
What is a GSTIN?
GSTIN (Goods and Services Tax Identification Number) is a unique 15-character alphanumeric code assigned to every GST-registered business in India. It serves as the primary identifier on tax invoices.
How is a GSTIN structured?
The 15 characters are: 2-digit state code + 10-digit PAN + 1-digit entity number + 1 letter "Z" + 1 check digit. For example, 27AAAPL1234C1ZV has state code 27 (Maharashtra) and PAN AAAPL1234C.
Does this tool verify the GSTIN with the government portal?
No. This is a format and checksum validator — it confirms whether the GSTIN follows the correct structure and passes the official check-digit algorithm. To verify GST registration status, use the official GST portal at gst.gov.in.
What does the check digit tell me?
The 15th character is a computed check digit using a weighted modulo algorithm defined by GSTIN standards. If the check digit is wrong, the GSTIN is definitively invalid regardless of other characters.
What are common reasons a GSTIN fails validation?
Typos in the PAN segment, incorrect state code (e.g. code 99 does not exist), entity number out of range (must be 1–9 or A–Z), or a mistyped check digit are the most frequent causes.