Canada Pension Plan (CPP) is the amount deducted from your each pay cheque subject to the annual limit. Your employer also contributes an equal amount to your CPP. Your contribution and your employer’s contributions both go to investment funds for growth. When you reach the age of 65, you are eligible to apply for your CPP benefit and get paid. The amount paid to you every year will depend on how much total you have contributed through your employment and self-employment.
Old Age Security (OAS) is funded by the Government of Canada. You do not contribute to your Old Age Security. You are eligible to apply for your OAS after the age of 65. The amount you will get every year from your OAS will depends how long have you lived in Canada after the age of 18.
Your Pension (CPP) and Old Age Security (OAS) payments are taxable for the income tax purposes in Canada.
At the end of the year, the Government of Canada reports your CPP and OAS on T4(P) and T4(OAS) to CRA and mails you a copy of the same.
If you get a pension from a foreign country, it will also be taxable in Canada if you are the resident of Canada.