Versions of s. 146(1), definition “unused rrsp deduction room”, para (b)

for taxation years that end after 1990, the amount, which can be positive or negative, determined by the formula A + B + R - (C + D) where A is the taxpayer’s unused RRSP deduction room at the end of the preceding taxation year, B is the amount, if any, by which the lesser of the RRSP dollar limit for the year and 18% of the taxpayer’s earned income for the preceding taxation year exceeds the total of all amounts each of which is the taxpayer’s pension adjustment for the preceding taxation year in respect of an employer, or a prescribed amount in respect of the taxpayer for the year, C is the taxpayer’s net past service pension adjustment for the year, D is the total of all amounts each of which is an amount deducted by the taxpayer under any of subsections (5) to (5.2), in computing the taxpayer’s income for the year, an amount deducted by the taxpayer under paragraph 10 of Article XVIII of the Canada-United States Tax Convention signed at Washington on September 26, 1980 or a similar provision in another tax treaty, in computing the taxpayer’s taxable income for the year, a contribution made by an employer in the year to a pooled registered pension plan in respect of the taxpayer, or the amount, if any, by which the taxpayer’s exempt-income contribution amount (as defined in subsection 147.5(1)) for the year exceeds the taxpayer’s unused non-deductible PRPP room (as defined in subsection 147.5(1)) at the end of the preceding taxation year, and R is the taxpayer’s total pension adjustment reversal for the year. (déductions inutilisées au titre des REER)

for taxation years that end after 1990, the amount, which can be positive or negative, determined by the formula A + B + R - (C + D) where A is the taxpayer’s unused RRSP deduction room at the end of the preceding taxation year, B is the amount, if any, by which the lesser of the RRSP dollar limit for the year and 18% of the taxpayer’s earned income for the preceding taxation year exceeds the total of all amounts each of which is the taxpayer’s pension adjustment for the preceding taxation year in respect of an employer, or a prescribed amount in respect of the taxpayer for the year, C is the taxpayer’s net past service pension adjustment for the year, D is the total of all amounts each of which is an amount deducted by the taxpayer under any of subsections (5) to (5.2), in computing the taxpayer’s income for the year, an amount deducted by the taxpayer under paragraph 10 of Article XVIII of the Canada-United States Tax Convention signed at Washington on September 26, 1980 or a similar provision in another tax treaty, in computing the taxpayer’s taxable income for the year, a contribution made by an employer in the year to a pooled registered pension plan in respect of the taxpayer, or the amount, if any, by which the taxpayer’s exempt-income contribution amount (as defined in subsection 147.5(1)) for the year exceeds the taxpayer’s unused non-deductible PRPP room (as defined in subsection 147.5(1)) at the end of the preceding taxation year, and R is the taxpayer’s total pension adjustment reversal for the year.

for taxation years that end after 1990, the amount, which can be positive or negative, determined by the formula A + B + R - (C + D) where A is the taxpayer’s unused RRSP deduction room at the end of the preceding taxation year, B is the amount, if any, by which the lesser of the RRSP dollar limit for the year and 18% of the taxpayer’s earned income for the preceding taxation year exceeds the total of all amounts each of which is the taxpayer’s pension adjustment for the preceding taxation year in respect of an employer, or a prescribed amount in respect of the taxpayer for the year, C is the taxpayer’s net past service pension adjustment for the year, D is the total of all amounts each of which is an amount deducted by the taxpayer, under subsection (5) or (5.1) or paragraph 60(v), in computing the taxpayer’s income for the year, or under paragraph 10 of Article XVIII of the Canada-United States Tax Convention signed at Washington on September 26, 1980 or a similar provision in another tax treaty, in computing the taxpayer’s taxable income for the year, and R is the taxpayer’s total pension adjustment reversal for the year.