All Canadian employees and self employed individuals, must contribute to CPP until they are 65. If you are employed, your employer deducts CPP contributions from your salary and remits them to CRA monthly. If you are self employed (earning business or professional income), CPP is calculated on your personal tax return and is paid by you, upon return submission.

At the age of 65, you are eligible to ELECT to stop contributing to the CPP. At the age of 70, no CPP contributions should be made, regardless of an election.

If you are an employee (in all provinces, except Quebec), an employee can elect to stop contributing to the CPP by completing form CPT30: CPT30 Election to Stop Contributing to the Canada Pension Plan, or Revocation of a Prior Election - Canada.ca. The form is very simple. One copy should be given to your employer and an original, mailed to CRA to the address shown on the form. 

The election takes effect, on the first month, following the election. For example, if you signed the form, on Jan 24, 2022, your employer can stop contributions on Feb 1, 2022.

This election can be revoked if needed.

If you are self employed, do not complete form CPT30. Instead, complete the applicable section of schedule 8: 5000-S8 Schedule 8 - Canada Pension Plan Contributions and Overpayment (for all except QC) - Canada.ca and attach it with your personal tax return (T1). To be valid, an election that begins in a specific 2021, must be filed on or before June 15, 2023.

The earliest, one can elect is the month of 65th birthday. If your birthday is in June, the earliest you can elect is June.

If your situation doesn't change, the election will stay in effect until you turn 70 OR until you revoke the election.

If you are both employed and self employed - elect to stop contributions on employment income by completing form CPT30. As above, give a copy of the form to your employers and send the original to CRA. The election takes effect, in the month following the election and will apply to your employment and self employment income. If you want to elect to stop contributing to the CPP on your self-employment earnings (this only applies if you are resident in a province or territory other than Quebec) on an earlier date in 2021 than the effective date of the CPT30, you need to complete schedule 8 (outside of Quebec).