From CRA:
"Registered retirement savings plan (RRSP) income
If you earn exempt income only and you have contributed to an RRSP, you cannot deduct your contributions on your tax return. By the same token, any withdrawals of your original RRSP contributions will not be taxable. However, since your exempt income did not create any RRSP contribution room, you will have to pay a penalty under Part X.1 of the Income Tax Act for your non-deductible contributions to your RRSP. Any investment earnings you withdraw from the RRSP will be taxed in the same way as interest and investment income.
If you earn taxable income and contribute to an RRSP, the normal rules on claiming RRSP deductions apply to you (i.e., contributions will be deductible within the allowable limits based on earned income, and all withdrawals will be taxable)."
