Final answer:
Commissions are included in regular salary calculations for the purposes of calculating Canada Pension Plan contributions. There is no separate formula for commission payments; they are treated like any other wage or salary.
Step-by-step explanation:
When calculating Canada Pension Plan (C/QPP) contributions on earnings that include commissions, the correct approach is to include commissions in regular salary calculations. This means that for commissions paid regularly with salary or even for commission-only earners, all amounts are subject to C/QPP contributions just as any other salary or wage would be. No separate formula is used specifically for commission payments when determining the contribution amounts.