Please review the following information to help me better understand the problem and double-check the information added.

Was the CPT16 form specifically approved by the CRA for this person?

Under the 'Setting Up' or 'Profile' section, did you check the box for 'CPP Exempt'?"

TurboTax often has a "Personal Profile" page at the very beginning. If the box for "I was exempt from CPP" isn't checked there, the software will ignore any manual changes you try to make to Schedule 8 later.

Are there any T4 slips entered with Box 28 (CPP/QPP Exempt) left blank?"

Why: If they have even a small amount of employment income (T4), and Box 28 is not checked "Exempt" on that slip, TurboTax will force a CPP calculation on the T2125 income as well to "match" the T4.

Does the error happen at the 'Review' stage or when you actually hit 'Transmit' (NetFile CRA)?