What factors determine your maximum RRSP contribution?
Generally speaking, the maximum RRSP contribution is the lesser of 18% of the income you earned in the previous year, and the contribution limit of $25,370 (for 2016). This maximum contribution amount might be reduced if you participated in a pension plan or a deferred profit sharing plan through an employer in the preceding year.
That said, unused RRSP contribution room from previous years can increase the maximum allowable contribution amount.
Income earned includes salaries and commissions, rental income and income from some other sources, but notably excludes investment income.