# Social Insurance number masking

The Data Masking transformation masks a Social Insurance number that is nine digits. The digits can be delimited by any set of characters.

If the number contains no delimiters, the masked number contains no delimiters. Otherwise the masked number has the following format:

xxx-xxx-xxx

### SIN start digit

You can define the first digit of the masked SIN.

To set a start digit, enable Start Digit and enter the digit. The Data Masking transformation creates masked Social Insurance numbers that start with the number that you enter.

### Repeatable Social Insurance numbers

You can configure the Data Masking transformation to return repeatable SIN values. When you configure a field for repeatable SIN masking, the Data Masking transformation returns deterministic masked data each time the source SIN value and seed value are the same. To return repeatable SIN numbers, enable Repeatable Values and enter a seed number.

The Data Masking transformation returns unique values for each Social Insurance number.