Social Insurance Numbers are verified using the method prescribed by the Government of Canada. Numbers that do not pass this verification are rejected and will not be stored in an employee's record.
The verification method is described below.
A SIN has nine digits.
The first eight digits is the basic 'number'.
The ninth digit is a check digit.
Verification method:
Example SIN: 193-456-787.
Basic number: 193 456 78 Check digit: 7
Make a number from each alternate position to the left beginning at the second digit
9 4 6 8
Add the numbers to themselves
9 4 6 8
9 4 6 8
18 8 12 16
Cross-add the digits in the sum
(1 + 8 + 8 + 1 + 2 + 1 + 6) = 27
Add each alternate digit beginning at the first digit
(1 + 3 + 5 + 7) = 16
Sum the two results: 27 + 16 = 43
If the total is a multiple of 10, the check digit should be 0
Otherwise, subtract the total (43) from the next highest number ending in zero (50).
The check digit is (50 - 43) = 7