Brazilian voter ID validation rules
A Brazilian voter ID has 12 digits: 8 for the issuance sequence, 2 for the electoral state code and 2 chained check digits, the second depending on the outcome of the first. That chaining, more than the modulo-11 math itself, is what usually causes bugs for anyone copying CPF validation logic wholesale.
A remainder of 9 is neither 10 nor 0, so no special rule applies: the first check digit is simply the remainder.
The 9 used here comes from the first check digit computed in the previous step, which is exactly why the second digit calculation cannot run before the first.
Swapping only the state code (from 01 to 20) changes the second check digit from 1 to 7 without touching the first, proof that the first digit depends on the sequential block alone.
Yes. The number includes two check digits calculated from the sequence and state code.
Historically, a check digit of 0 for those two specific codes caused ambiguity in manual voter-registry processing; the rule forces the value to 1 in that specific case, so a validator that skips this exception will flag a legitimate state 01/02 voter ID as invalid.
You can write it as a single function, but the internal computation stays sequential: the second check digit uses the first one numeric value as one of its three summed terms, so trying to parallelize them, or computing both from just the sequential block and state code without that dependency, produces an invalid number.
Yes, the calculation for both check digits is identical across all 28 codes, including 28 reserved for voters abroad; the only rule that changes per code is the remainder-0-becomes-1 exception, and it applies only to codes 01 and 02, not to 28.
Confirm the two digits form a number between 01 and 28 inclusive; anything outside that range (00, or 29 and above) does not correspond to any real state or abroad-voter code, so validation should reject it before even attempting the second check digit calculation.
Generation happens locally in the browser. Analytics receives only action, status, type and format, never the generated voter ID.