In the same way your regular CAAT Plan contributions are tax deductible, a service purchase will be deductible if you pay in cash and have RRSP contribution room. This "room" for the current year is determined by your Pension Adjustment (PA) amount - that is, the deemed value, calculated by your employer, of the pension benefit you earned in the previous year.
A Past Service Pension Adjustment (PSPA) is the deemed value of the additional benefit created by the purchase - it reduces your RRSP contribution room. To create room for the purchase within your RRSP, you may need to withdraw some funds from it, which will be considered taxable income in the year the funds are withdrawn, or you may need to transfer funds from your RRSP to purchase the leave.
Keep in mind: A purchase may affect your PA amount. If you pay for a leave of absence before April 30 of the year after the leave ends, it will be included in the PA reported for the period.
If you choose to buy the leave after April 30 of the following year, we will calculate a PSPA and send it for approval to the Canada Revenue Agency.
Note that PAs have been used since 1990. These calculations are not required for service periods before that year. However, there are some other tax issues, such as the pre-1990 deductibility limit of $3,500, which you would need to consider.
Federal law places a maximum on the amount of post-1990 unpaid leaves of absence you can purchase. The total amount is 5 years, plus an additional 3 years for pregnancy or parental leave.
Your decision to make a purchase will be affected by the issues of tax deductibility, PAs and the possibility of a PSPA.