GST Number (GSTIN) Instant Verifier & MOD 36 Taxpayer Lookup
Mathematically verify 15-digit Indian GST numbers online for free. Decode state codes, embedded business PAN, and entity registration numbers with official MOD 36 checksum calculation to detect fake GST bills.
GST Number (GSTIN) Instant Verifier
MOD 36 ALGORITHMVerify 15-digit GST numbers, decode PAN and State, and export printable vendor due diligence slips.
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Key Technical Features & Architecture
Mathematically validates the 15th checksum character using the official GST Council MOD 36 polynomial algorithm.
Instantly isolates and decodes the 10-character business PAN, entity classification, and state jurisdiction code.
Verify supplier tax credentials before booking Input Tax Credit (ITC) under CGST Act Section 16(2)(c).
15-Character Indian GSTIN Structural Anatomy (GST Rules 2017)
Authoritative standards, formatting thresholds, and official regulatory guidelines:
| Character Position | Designated Purpose | Valid Value Range & Description |
|---|---|---|
| Characters 1 & 2 | State / Union Territory Code | 01 (J&K) to 38 (Ladakh) based on Indian Census 2011 |
| Characters 3 to 12 | Permanent Account Number (PAN) | 10-character alphanumeric legal PAN of business entity |
| Character 13 | Entity Registration Number | 1 to 9, then A to Z representing registration count in that state |
| Character 14 | Default Alphabetical Constant | Letter "Z" by default (reserved for future statutory use) |
| Character 15 | Check Digit (MOD 36 Checksum) | Alphanumeric character calculated using ISO 7064 Mod 37, 36 |
| ITC Compliance Rule | Valid Active GSTIN Required | Non-compliant invoices trigger 100% ITC reversal + interest |
How to Verify a GST Number in 5 Steps
Follow this verified 5-step process for instant compliance and verified results:
Enter 15-Character GSTIN
Type or paste the 15-character GST number printed on your invoice or purchase order.
State Code Verification
The engine validates the first two digits against official Indian Census state codes.
Extract Embedded PAN
Inspect characters 3 to 12 to verify business structure (Company, Firm, Individual, LLP).
Calculate MOD 36 Checksum
The algorithm computes the expected 15th digit and compares it with your supplier number.
Audit Invoice Legality
Confirm active mathematical validity and launch direct verification on the GST Portal.
Common GSTIN Verification Errors & Invoice Fraud
Avoid common formatting errors, legal omissions, and calculation pitfalls:
Fabricated or Typo-Riddled GSTIN on Invoice
Fraudulent vendors often fabricate a random 15-character string. Kagazo runs the official MOD 36 formula to immediately catch fake checksums and unverified vendor invoices.
Alphanumeric OCR Transcription Mistakes
Scanning printed bills frequently misreads the number zero (0) as the letter (O) or one (1) as (I). Kagazo flags structural pattern violations based on expected alphanumeric slots.
Missing the Mandatory Default Constant
Under Indian GST specifications, character 14 is hardcoded to "Z" by statutory mandate. Any number with a different 14th character is structurally invalid.
Claiming Tax Credits on Cancelled Registrations
If a supplier registration was cancelled prior to the invoice date, tax authorities disallow Input Tax Credit under Section 16(2)(c). Always verify active registration status.
Frequently Asked Questions
Comprehensive technical, legal, and operational answers
Q1.What is a GSTIN and how is it constructed?
A Goods and Services Tax Identification Number (GSTIN) is a unique 15-digit alphanumeric identifier assigned to every registered taxpayer in India under the GST Act. It consists of: State Code (2 digits) + PAN (10 chars) + Entity Code (1 char) + "Z" (1 char) + Checksum (1 char).
Q2.How does the MOD 36 Checksum calculation work?
The 15th character is computed using a weighted polynomial algorithm (ISO 7064 Mod 37, 36) applied to the preceding 14 characters. It provides instantaneous offline mathematical verification that the number was generated by the GSTN portal.
Q3.Can I check the business entity type from the GSTIN?
Yes. The 4th character of the embedded PAN indicates entity type: "C" for Company, "P" for Person/Individual, "H" for HUF, "F" for Partnership Firm, "A" for Association of Persons, "T" for Trust, and "L" for Local Authority.
Q4.What happens if I accept a tax invoice with an invalid or fake GSTIN?
Under Section 16(2)(c) of the CGST Act, you cannot claim Input Tax Credit (ITC) for taxes paid on fake or invalid invoices. The tax department will demand reversal of ITC along with 18% annual interest and penalties.
Q5.Is my searched GST number logged or shared on your servers?
No. Kagazo performs all structural and mathematical checksum validations entirely client-side inside your browser JavaScript engine. Zero vendor GSTINs or business queries are logged on our servers.
Q6.What are the official state codes for major Indian states in GSTIN?
Common state codes include: 33 for Tamil Nadu, 27 for Maharashtra, 29 for Karnataka, 07 for Delhi, 09 for Uttar Pradesh, 24 for Gujarat, 19 for West Bengal, 32 for Kerala, 36 for Telangana, and 37 for Andhra Pradesh.
Q7.What does the 13th character represent in a GSTIN?
The 13th character represents the registration count of that specific PAN holder within that state. It begins with "1" for the first registration, "2" for the second vertical, up to "9", and then continues as "A", "B", etc.
Q8.Can I verify the live filing status of a supplier on the official portal?
Yes. After performing instant structural and checksum verification on Kagazo, you can click through to the official GST Portal (services.gst.gov.in) to inspect active/cancelled status and GSTR-3B return filing history.
Q9.Why is the 14th character always the letter "Z"?
The 14th character was reserved as the default constant "Z" in the original GST Council architecture to allow future expansion of registration types without breaking existing 15-digit database schemas.
Q10.Does this tool verify composition scheme dealers?
Composition dealers have standard 15-digit GSTINs that pass mathematical MOD 36 verification. However, composition dealers cannot issue Tax Invoices or collect GST from customers; they must issue a "Bill of Supply".