VyaparStack
    VyaparStack
    Tax SimulatorCapabilitiesSavings ToolPricingStatutory FAQBlog
    100% CBIC Rule 46 & Section 31 Compliant

    Need Section 31 Tax Invoices with Direct UPI Settlements?

    Stop losing 2% to payment gateways. VyaparStack generates consecutive alphanumeric invoices, embeds NPCI UPI QR codes for instant 0% settlement, and exports GSTR-1 Table 4A JSON.

    Launch Free Sandbox
    VyaparStack
    VyaparStack

    Automated CGST/SGST/IGST tax calculations, Section 31 compliant PDF tax invoices, and instant zero-fee NPCI UPI QR settlements for Indian freelancers, consultants, and solopreneurs.

    Product

    • Tax Simulator
    • Statutory Capabilities
    • Savings Calculator
    • Pricing Plans
    • Free Tools Suite →
    • Compliance Blog
    • Statutory FAQ

    Free Statutory Tools

    • GSTIN Validator
    • Reverse GST Calculator
    • SAC Code Finder
    • UPI QR Generator
    • MSME Interest Engine

    Statutory & Legal

    • About Platform
    • Terms of Service
    • Privacy Policy (DPDPA)
    • Contact Support
    © 2026 VyaparStack. All rights reserved. CGST Act Section 31 Compliant Architecture.
    Home/Free Tools/GSTIN Validator
    Statutory Luhn Mod-36 Checksum Engine

    Indian GSTIN Format & Checksum Validator

    Instantly verify any 15-character Goods and Services Tax Identification Number (GSTIN). Validates statutory structure, identifies state jurisdiction, decodes PAN entity classification, and calculates the 15th Luhn Mod-36 check digit.

    Format: 2 Digits State + 10 Alphanumeric PAN + 1 Entity Serial + 1 'Z' + 1 Check Digit

    Valid Statutory GSTIN (Structure & Checksum Verified)Passes Central Board of Indirect Taxes & Customs (CBIC) Section 31 format specifications.
    State Jurisdiction (Chars 1-2)

    Maharashtra (Code: 27)

    Determines Intra-State (50/50 CGST/SGST) vs Inter-State (100% IGST)

    PAN of Registered Entity (Chars 3-12)

    AAPFU0939F

    Official Income Tax Permanent Account Number

    Entity Category (Char 4 of PAN)

    Partnership Firm / LLP

    Identifies whether counterparty is Individual, Company, LLP, or Trust

    15th Checksum Digit (Luhn Mod-36)

    Digit: V (Expected: V)

    Mathematical integrity check prevents typographical billing errors

    Raise Section 31 Invoice to this GSTINAll Free Tools

    Understanding Indian GSTIN Anatomy & Legal Rules

    Statutory framework under CGST Act Section 22 to Section 25 and Rule 46 invoice particulars.

    Why must an invoice contain the client's verified GSTIN?

    Under CGST Rule 46(d), a registered supplier issuing an invoice exceeding ₹50,000 (or any registered B2B supply) must mandatorily state the name, address, and GSTIN/UIN of the recipient. Failure prevents the buyer from claiming Input Tax Credit (ITC) under Section 16(2) and can attract penalties under Section 122(1)(i).

    How does the 15th Checksum Digit work?

    The GST Council mandates a modified Luhn algorithm (Modulo 36) over the base-36 alphanumeric characters (0-9, A-Z). Alternate characters are weighted by 1 and 2, and the sum of products modulo 36 yields the statutory check digit. This ensures fraudulent or mistyped GST numbers are rejected immediately before filing GSTR-1.