Social Insurance Number check digit

[onomatopoeia]

The first eight numbers of a Canadian Social Insurance Number determine the value of the ninth digit. Here's how it works:

1) Multiply the first, third, fifth and seventh numbers by one.

2) Multiply the second, fourth, sixth and eighth numbers by two. If any of the 2nd, 4th, 6th or 8th numbers are greater than four, add the two digits of the multiplication product together.

3) Add the products of the eight adjusted multiplications.

4) Subtract the sum of 3) from a multiple of ten equal to, or next above, this sum. The result is the ninth digit of the SIN.

Here's an example, with a randomly chosen valid SIN:

4 0 9 7 3 5 6 8 [5]
X
1 2 1 2 1 2 1 2
----------------------
= 4 0 9 14 3 10 6 16

4+0+9+(1+4)+3+(1+0)+6+(1+6)=35

40-35=5

 

[Sonic Temple]

Interesting - actually very cool.

 

[JeanGary Diablo]

This must be either an old way or a new way of calculating the last number. I tried it with my SIN, but the resulting number doesn't match the last number of my SIN (checked my work twice). Still, pretty cool stuff.

 

[shack]

Not questioning the veracity of this formula.

The question is, is of what value or use is this info?

 

[onomatopoeia]

Not questioning the veracity of this formula.

The question is, is of what value or use is this info?

Suppose that you are an employer, and someone newly hired has submitted an invalid SIN. This could be a dyslexic error, carelessness, a data entry error, or someone knowingly using a false SIN, for any of a number of reasons. It would screw up tax witholding, CPP/EI premiums, etc., if part of a year was paid to multiple SINs of the same person. Not enough taxes would be withheld, because the pro rated basic exemption amount would probably be applied to each SIN. Many accounting programs would assign a SIN starting with 999, to make them easy to find in sorted data.

 

[superstar_88]

Ok so we've determined that Diablo is an illegal alien using a bogus SIN. The RCMP will be knocking on your door shortly.