What does each part of a GSTIN mean?

The first two digits are the state code. The next ten characters are the holder’s PAN. The 13th and 14th are an entity code: in practice a number for each registration under that PAN in the state, then Z. The 15th is a check character.

How is the GSTIN check digit calculated?

No official text gives the method. Open-source checkers use Luhn mod 36: each of the first 14 characters becomes a number (0–9, then A = 10 to Z = 35), every second one is doubled, each product adds its quotient and remainder by 36, and the check character is what brings the total to a multiple of 36.

Can I find the PAN from a GSTIN?

For a regular GSTIN, yes: characters 3 to 12 are the PAN. A TDS deductor may be registered with a TAN instead, and a non-resident may have no PAN at all.

Why does one business have more than one GSTIN?

Registration is state by state, so a business has a GSTIN in each state it supplies from. Within a state it can also take a separate registration for each place of business.

Does a valid result mean the GSTIN is active?

No. It means the number is built correctly and its check character adds up. Only Search Taxpayer on the GST portal shows whether a GSTIN is active or cancelled, and whose it is.

Is what I type saved or sent anywhere?

No. Every check, including a file you open, runs in your browser. Nothing is sent, stored or tracked by the tool.

Does PrimoERP use the GSTINs on my invoices?

Yes. PrimoERP puts GST on every invoice and sets the place of supply from your GSTIN and your customer’s, then applies CGST and SGST or IGST.

GSTIN Validator: Check GST Numbers in Bulk

GSTIN validator

A valid format is not a live registration.

This tool checks how a GSTIN is built and whether its check character adds up. It can’t tell you whether the GSTIN was issued, is still active, or belongs to the business that gave it to you. Only the GST portal’s Search Taxpayer can.

Search Taxpayer on the GST portal

Check one GSTIN

GSTIN

15 characters. Spaces, hyphens and lower case are fine.

What it says

Valid formatThe pattern and the check character agree.

State codeMaharashtra: 27
PAN: AAPFU0939F
PAN’s 4th letter (holder type): F
Entity codeusually registration no. 1 under this PAN in Maharashtra: 1
14th character: Z
Check characterV, as expected: V

How the check character is worked out

Each of the first 14 characters, its value, and what it adds
Place	Character	Value	×	Product	Adds
1	2	2	1	2	2
2	7	7	2	14	14
3	A	10	1	10	10
4	A	10	2	20	20
5	P	25	1	25	25
6	F	15	2	30	30
7	U	30	1	30	30
8	0	0	2	0	0
9	9	9	1	9	9
10	3	3	2	6	6
11	9	9	1	9	9
12	F	15	2	30	30
13	1	1	1	1	1
14	Z	35	2	70	35

Total 221. 221 ÷ 36 leaves 5, and (36 − 5) mod 36 = 31, which is V.

Worked out in your browser. Nothing you type or open leaves this page.

Check a list

Paste GSTINs one per line, or separated by commas, semicolons or spaces, or open a .txt or .csv file. Other words in the file, such as names and headings, are left out.

GSTINs to check

Repeats are counted once. Read in your browser, never uploaded.

4 checkedValid format: 1Not valid: 2Not a regular GSTIN: 11 repeat left out

Download as CSV

Results
#	GSTIN	Result	Reason	State	PAN
1	27AAPFU0939F1ZV	Valid format	The pattern and the check character agree.	27 Maharashtra	AAPFU0939F
2	27AAPFU0939F1ZO	Not valid	The check character should be V, not O. A character is probably mistyped.	27 Maharashtra	AAPFU0939F
3	27AAPFU0939F1Z	Not valid	It has 14 characters. A GSTIN has 15.
4	27AAPFU0939F1AA	Not a regular GSTIN	The 14th character is A. A regular GSTIN has Z there, so this is a typo or a special registration.	27 Maharashtra	AAPFU0939F

How a GSTIN is built.

What the official texts say about the 15 characters, and who gets a number that doesn’t follow the pattern.

A GSTIN has 15 characters: the first 2 are the state code, the next 10 are the PAN of the legal entity, the next 2 are an entity code, and the last is a check sum.
Source: GST Council, “Registration under GST Law”, checked 17 Oct 2026
Registration is PAN based and state specific: a supplier registers in each state or union territory it supplies from.
Source: GST Council, “Registration under GST Law”, checked 17 Oct 2026
A person with more than one place of business in a state may be granted a separate registration for each, so one PAN can hold several GSTINs in one state.
Source: CGST Act 2017, s.25(2), proviso, checked 17 Oct 2026
A PAN is needed for registration, but a person who deducts tax under section 51 (TDS) may have a TAN instead.
Source: CGST Act 2017, s.25(6), proviso, checked 17 Oct 2026
On the GST portal, a TDS applicant without a PAN selects TAN and enters it.
Source: GST portal FAQs, tax deductor, checked 17 Oct 2026
A non-resident taxable person doesn’t need a PAN: a passport number, or the tax identification number of their own country, will do.
Source: GST portal FAQs, non-resident taxable person, checked 17 Oct 2026
UN bodies, embassies and other notified persons get a Unique Identity Number (UIN). GSTN gives its pattern as 22YYAAA99999UIN: state code, year, country code, a five-digit serial, then UIN (or ONP for another notified person).
Source: GSTN, FAQs on registration (part 2), checked 17 Oct 2026
The GST system’s state code list gives 01 to 38 for the states and union territories, 97 for “Other Territory”, and 96 and 99 for “Other countries”.
Source: E-invoice system, master codes, checked 17 Oct 2026
A tax invoice must show the supplier’s GSTIN, and the recipient’s GSTIN or UIN when the recipient is registered.
Source: CGST Rules 2017, rule 46(a) and (d), checked 17 Oct 2026
The GST portal’s Search Taxpayer takes a GSTIN, UIN or PAN and shows the legal name, trade name, date of registration, taxpayer type and the GSTIN’s status, so you can check a GSTIN is genuine.
Source: GSTN, Welcome Kit for New Businesses, §3.4, checked 17 Oct 2026

Where the rules are silent

How the check character is worked out. The official texts say only that the last character is a check sum; we found no official page that gives the method. The tool uses Luhn mod 36, the method open-source checkers such as python-stdnum use. A failed check means a character is very likely mistyped, but the GST portal has the final word.
What the entity code holds. The texts call characters 13 and 14 an entity code without saying what they hold. In regular GSTINs the 13th tells registrations under one PAN in a state apart (1 to 9, then A to Z) and the 14th is Z. The tool expects that, and calls anything else “not a regular GSTIN” rather than invalid.
The PAN’s 4th letter. It stands for the kind of holder, such as a company or an individual. The Income Tax Department sets those letters and no GST text lists them, so the tool shows the letter as it is and doesn’t judge it.
Special registrations. UINs, non-resident registrations and TAN-based TDS registrations follow other patterns, and no official text we found gives check rules for them. The tool marks them “not a regular GSTIN” and leaves them to Search Taxpayer.
Old state codes. 25 (Daman and Diu) and 28 (Andhra Pradesh’s old code) still decode, marked as old codes. Check any GSTIN that starts with them on the portal.

One GSTIN, step by step.

27AAPFU0939F1ZV, a sample from python-stdnum’s test cases, taken apart and its check character worked out.

State codeMaharashtra: 27
PAN, characters 3–124th letter F: AAPFU0939F
Entity code and 14th character: 1 Z
Odd places, × 12 + 10 + 25 + 30 + 9 + 9 + 1: 86
Even places, × 214 + 20 + 30 + 0 + 6 + 30 + 35: 135
Total, and what’s left ÷ 36: 221 → 5
Check character36 − 5 = 31 = V: V

Digits count as themselves and letters as A = 10 to Z = 35. A product of 36 or more adds its quotient and remainder: Z is 35, 35 × 2 = 70 = 1 × 36 + 34, so it adds 1 + 34 = 35. The 15th character given is V, so the check passes.

A sample used in open-source tests, not a business we know of. A passing check says nothing about whether a GSTIN is registered or active.

What it does not check.

Look these up on the GST portal’s Search Taxpayer before you rely on a GSTIN.

Whether the GSTIN is active
A valid format doesn’t mean the GSTIN was ever issued, or that it hasn’t been cancelled.
Search Taxpayer shows the GSTIN’s status and its date of cancellation, if any.
Source: GSTN, Welcome Kit for New Businesses, §3.4, checked 17 Oct 2026
Who it belongs to
The number doesn’t carry a name. A real GSTIN copied onto someone else’s invoice passes every check here.
Search Taxpayer shows the legal name and trade name of the business behind a GSTIN.
Source: GSTN, Welcome Kit for New Businesses, §3.4, checked 17 Oct 2026
Return filing
Whether a supplier files its returns isn’t in the number. Search Taxpayer shows a return filing table.
Whether the PAN exists
The tool checks that characters 3–12 have a PAN’s shape: five letters, four digits, a letter. It can’t tell whether the Income Tax Department issued that PAN.
UINs, non-resident and TDS registrations
They follow other patterns. The tool marks them “not a regular GSTIN” instead of passing or failing them.
A non-resident taxable person may be granted registration on the basis of documents other than a PAN.
Source: CGST Act 2017, s.25(7), checked 17 Oct 2026
Very large files
Files up to 5 MB are read in your browser. The table shows the first 500 rows; the CSV download has every row.

More GST and compliance tools.

Work out GST, check a GSTIN, see whether e-invoicing or an e-way bill applies, and keep the due dates. And the tools that go with this one.

GST calculatorAdd or remove GST on one amount or a whole bill, split into CGST, SGST or IGST.Read more E-invoice applicability checkerWhether your business must issue e-invoices, and the 30-day reporting limit.Read more E-way bill checkerWhether a consignment needs an e-way bill, and how long the bill stays valid.Read more GST late fee and interest calculatorLate fee and interest on a late GSTR-3B, GSTR-1 or GSTR-9, day by day.Read more Compliance calendarGST, TDS, PF and ESI due dates, month by month, to add to your calendar.Read more GST invoice generatorA GST tax invoice with every required field, as a PDF or an Excel template.Read more Purchase order generatorA purchase order with GST, delivery and payment terms, as a PDF or Excel.Read more Delivery challan generatorA delivery challan with the details Rule 55 lists, as a PDF or Excel.Read more All free toolsGST, invoices, payroll, inventory and accounting tools, free and with no signup.Read more

The right GST from both GSTINs.

PrimoERP reads your GSTIN and your customer’s on every invoice and applies the tax that follows.

GST accounting softwarePrimoERP compares your GSTIN with your customer’s and the place of supply, then applies CGST and SGST or IGST.Read more GST e-invoicingEach e-invoice is reported to the IRP from your books, with its IRN and QR code printed on it.Read more Trading and distributionOrder to invoice in one step, with price lists per customer, credit limits and stock per warehouse.Read more How to migrate from TallyWhen to switch, what to export from TallyPrime, GST and TDS balances, and a day-by-day cutover plan.Read more

GSTIN questions people ask.

1.

How do I check whether a GSTIN is valid?

In two steps. First the format: 15 characters with a state code, a PAN, an entity code and a check character that adds up, which this tool checks. Then whether it is real and active: search it on the GST portal’s Search Taxpayer.

— the PrimoERP team

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