I collect CPP monthly and worked in 2018. I opted to continue paying CPP premiums but the software is deducting it as a CPP overpayment. Is this correct?

To make the election or enter the details of a previous election to stop paying CPP on your Self-Employed earnings using TurboTax Online or in the EasyStep view, go to Income > T-Slips > T4A(P) Canada Pension Plan Benefits.

On the T4A(P) - Summary screen, you can enter your information about previous elections or choose to stop contributing to CPP on your self-employment earnings. You must say "Yes" to the question - "Did you elect to stop contributing to CPP on your self-employment earnings in a year prior to 2017?"

This screen will only appear if you were 65 to 70 years of age.