The review messages with respect to CPP and OAS should be modified to reflect tax planning decision made by the client.
CPP may be started early or deferred, but the review message is the same for any client over age 60. This can be overcome if the T4A(P) slip had a field to indicate the actual or planned start date for CPP. Review messages can be refined to flag missing CPP after the expected start date, or if the start date is set beyond the month after the 70th birthday.
OAS may be deferred. For form T4A(OAS), the same comments as those for CPP apply. Furthermore, the expected maximum amount of OAS can be adjusted for the 0.6% increase for each month the benefit was deferred.
Additional fields on each form would be helpful to indicate tax witholding changes requested/expected. The date and $ or % requested can be noted. It could even be used to generate form ISP 3520 (Request for Voluntary Tax Witholdings).
NB. All of the above should carryforward to the following year’s return.