Your pensionable service is a key part of the formula used to calculate your future pension. The more service you have when you retire, the larger your pension will be. You earn service for every day that you contribute to the Plan, but in some cases, you may also buy service.
If you were off work for a period of time and not paid (Leaves of Absence), this will create a gap in your pensionable service. You may be able to buy this service to ensure there is no service gap.
If you were paid out for the service you earned with another Registered Pension Plan (RPP), you may be able to use those funds to buy pensionable service in PSPP (Buying Prior Service).
We call this process of buying service a buyback.