The employer contribution to rpp does not reduce your taxable income. Your contributions do reduce the net and taxable income, and is reported in box 20 on your T4. Box 52 is the full amount that went into your rpp, so when you subtract box 20 from box 52 the balance is what the company contributed. The amount in box 52 does not affect your tax return, it is there for information purposes only. The amount in box 52 is used in the calculations your following year RRSP contribution limit.
