International · Validation
Taiwan national ID validator.
Check a Taiwan national identification number: one letter and nine digits, such as A123456789. Works for citizen IDs (1 or 2) and resident certificate numbers (8 or 9). Format and checksum only.
How it works: turn the letter into a two-digit value using the ministry's letter order (A = 10, B = 11 … O = 35). Add its tens digit and 9 × its units digit, then 8, 7, 6, 5, 4, 3, 2, 1 times digits 1 to 8, then the check digit. A valid number gives a total that is a multiple of 10.
Inputs
Result
Enter a number and press Validate.
How the Taiwan ID check works
| Step | What happens |
|---|---|
| 1 | Convert the letter with ABCDEFGHJKLMNPQRSTUVXYWZIO: A = 10, B = 11 … H = 17, J = 18 … N = 22, P = 23 … V = 29, X = 30, Y = 31, W = 32, Z = 33, I = 34, O = 35 |
| 2 | Letter contribution = tens digit + 9 × units digit |
| 3 | Multiply digits 1 to 8 by 8, 7, 6, 5, 4, 3, 2, 1 and add; then add the final check digit once |
| 4 | If the grand total is a multiple of 10 the number passes |
Worked example
A123456789: A = 10 gives 1 + 0×9 = 1. Digits: 1×8 + 2×7 + 3×6 + 4×5 + 5×4 + 6×3 + 7×2 + 8×1 = 120. Add the check digit 9: 1 + 120 + 9 = 130. 130 is a multiple of 10, so it passes.
What the second character means
For citizens the first digit is 1 for male and 2 for female. Resident certificate (ARC) numbers use 8 or 9 there. This tool reports the type it reads from that digit and does not check the letter against a household registration office.
Checksum only, not a register lookup
A passing result means the characters are consistent with each other. It does not confirm that the number was issued or that it belongs to anyone. Use it as a typo and format check. For the same kind of check on a Canadian number, see the SIN validator, or browse all ID and number validators.
Frequently asked questions
What does the letter in a Taiwan ID mean?
It marks the household registration office area where the ID was first issued, for example A for Taipei. It does not tell you where the holder lives today.
Is A123456789 a real ID?
It is the standard textbook example. It passes the checksum, which is why it is used in documentation, but it is not a real person's number.
Does this check Taiwan resident certificate numbers?
Yes. Numbers whose second character is 8 or 9 use the same weighted check.
Format and checksum only
This tool checks format and checksum entirely in your browser. It does not query any register, and a passing result is not proof the number was issued or belongs to anyone. Nothing you type is transmitted, stored, or logged.