India TAN Validator
Validate India Tax Deduction and Collection Account Numbers (TAN). QA.
How TAN validation works
The validator checks if the input is exactly 10 characters and matches the standard regex layout `AAAA11111A` (4 letters, 5 digits, 1 letter).
It evaluates the weighted Modulo 26 sum of the first 9 positions and confirms if the output maps to the 10th checksum letter.
Anatomy & Structure of the TAN (Tax Deduction Account Number)
The Indian TAN consists of 10 alphanumeric characters structured in 4 parts:
| Position | Field | Length | Meaning & Rule | Example |
|---|---|---|---|---|
| 1 to 3 | Jurisdiction Code | 3 letters | Official tax office jurisdiction code | MUM |
| 4 | Deductor Initial | 1 letter | First letter of the deductor's name (TDS/TCS entity) | A |
| 5 to 9 | Sequential Number | 5 digits | Sequential number generated by the tax authority | 12345 |
| 10 | Check Character | 1 letter | System-generated alphabetic check letter | B |
Official TAN Validation (Income Tax Act Section 203A)
Structural validation rules for Indian TAN:
^[A-Z]{4}[0-9]{5}[A-Z]$
- 1. Verify exact length of 10 alphanumeric characters.
- 2. First 4 characters must be uppercase letters (3 jurisdiction + 1 initial).
- 3. Positions 5 to 9 must contain exactly 5 numeric digits.
- 4. The 10th character must be an uppercase check letter.