India GSTIN Generator
Online GSTIN generator for India tax testing and QA. Excellent for QA.
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About Goods and Services Tax Identification Number (GSTIN)
The GSTIN is a unique 15-character fiscal identification number assigned to every registered taxpayer in India under the Goods and Services Tax framework.
The layout integrates the taxpayer's 10-character PAN, prefixed by a 2-digit Indian state code, and finalized by a check digit calculated using an alternating Modulo 36 checksum.
Anatomy & Structure of the GSTIN (Goods and Services Tax Number)
The Indian GSTIN consists of 15 alphanumeric characters structured in 5 parts:
| Position | Field | Length | Meaning & Rule | Example |
|---|---|---|---|---|
| 1 & 2 | State Code | 2 digits | Official state/territory code (01 to 37 per Indian Census) | 27 |
| 3 to 12 | Entity PAN | 10 chars | Permanent Account Number of the entity (format AAAAA9999A) | AAPFU0939F |
| 13 | Entity Registration Count | 1 char | Number of registrations in the same state (1-9, A-Z) | 1 |
| 14 | Default Character | 1 char | Fixed character 'Z' by GSTN regulations | Z |
| 15 | Check Character | 1 char | Calculated via alternating Modulo 36 algorithm | 5 |
Official Algorithm (Alternating Modulo 36 — GSTN)
GSTIN uses alternating Modulo 36 with weights [1, 2, 1, 2...]:
factor = val * (pos%2 === 0 ? 1 : 2); sum += floor(factor/36) + (factor%36); Check = (36 - (sum%36))%36
- 1. Map each character to value 0-35 (0-9=0-9, A-Z=10-35).
- 2. Use weight 1 for even positions and weight 2 for odd positions.
- 3. Multiply character value by weight: factor = val × weight.
- 4. Add to sum: floor(factor / 36) + (factor % 36).
- 5. Take remainder modulo 36 and map to final check character.