I wonder if this is a left over from past years.  At one time, you stop contributing to CPP once you start collecting CPP pension.  That would explain the 1 month pro rating of the exemption.  I started collecting the pension in February.  Any thoughts?

There seems to be a bug in TurboTax Schedule 8 Part 4 Line 4.  I manually changed Box 23 (No. of Months-Retirement) of my T4A(P) to 12 months.  The 12 is used to determine the monthly proration for 2019 of the basic CPP exemption and maximum CPP pensionable earnings.  The value from this table is then inserted into Line 4 and others.

I think you have a problem TurboTax which may have shortchanged alot of people over the past 8 years.  Do you have a response to this?