Starting from tax year 2013, CRA introduces a new tax form RC381. It will replace Schedule 8 and CPP overpayment calculation part in form T2204. All CPP-related fields are calculated by form RC381. This is a major change in 2013 tax return. Therefore, Schedule 8 should not be in any 2013 tax return files.
Do a tax return validation, it will tell you how to do a tax return with form RC381.