GST Number Check (GSTIN Validator)
Paste or type a 15-character GSTIN below. This checks the format and the checksum digit, then decodes the state, embedded PAN, and entity number — entirely in your browser. Nothing is sent to any server.
Results and any AI-generated content from this tool are provided free, "as is", for general informational purposes only and may be inaccurate, incomplete, or out of date. Always verify the output yourself before relying on it — you use this tool and its results at your own risk.
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What is a GSTIN, and what does this checker actually verify?
A GSTIN (Goods and Services Tax Identification Number) is the unique 15-character code every GST-registered business in India is assigned. It isn't a random string — every character carries meaning: the first two digits are a state code, the next ten characters are the business's PAN (Permanent Account Number), the 13th character counts how many GST registrations that PAN holds within that state, the 14th is a fixed default character ("Z"), and the 15th is a checksum digit calculated from the other fourteen using a mod-36 algorithm. This tool decodes all of that and verifies the checksum instantly, entirely in your browser — no GSTIN you type here is ever sent anywhere.
Structure vs. registration status — an important distinction
A GSTIN can be structurally valid — correctly formatted, with a checksum that mathematically checks out — without being an active, currently-registered taxpayer. This tool only confirms the structure: that the format matches the standard pattern and the 15th character is the correct checksum for the first fourteen. It cannot tell you whether that GSTIN is currently active, cancelled, or was ever actually issued by the GST department, because that requires a live lookup against the government's own database. For that, use the official GST portal's "Search Taxpayer" tool — this checker is the fast first filter that catches typos and copy-paste errors before you go there.
Why the checksum step matters
Most GSTIN typos — a swapped digit, a dropped character, a letter that looks like a digit (O vs 0, I vs 1) — still happen to match the basic 15-character pattern, so a format-only check would wave them through. The checksum character is specifically designed to catch exactly this class of mistake: it's mathematically derived from the other fourteen characters, so almost any single-character typo changes the expected checksum and this tool flags it as invalid, even though the format still "looks" fine.
Reading the decoded breakdown
The state code tells you which state or union territory issued the registration (27 = Maharashtra, 29 = Karnataka, 33 = Tamil Nadu, and so on). The embedded PAN is the same 10-character PAN the business uses for income tax — its 4th character tells you the holder type (P = individual, C = company, F = firm, H = HUF, and a few others). The entity registration number shows how many separate GST registrations that exact PAN holds within that one state (usually "1", since most businesses register once per state).
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Frequently Asked Questions
No. It checks structure only — the 15-character format and the mod-36 checksum. To confirm a GSTIN is an active, currently registered taxpayer, use the official GST portal's "Search Taxpayer" tool.
No. Every check — format, state lookup, PAN decode, and checksum — runs entirely in your browser with JavaScript. Nothing is uploaded or logged.
The 15th character is calculated from the first 14 using a mod-36 algorithm. It catches typos — a single wrong character almost always produces a checksum mismatch, even when the overall format still looks correct.
The first 2 digits are a state code, the next 10 characters are the business's PAN, the 13th character counts registrations for that PAN in that state, the 14th is a fixed "Z", and the 15th is the checksum.
Either it doesn't match the standard pattern (e.g. lowercase letters, wrong character types in a position) or the checksum character doesn't match what the first 14 characters compute to — almost always a sign of a typo somewhere in the number.
