​You will have to pay a penalty if you owe tax and you file your tax return after the deadline.

If you file a late return once

If you file your return after the deadline and you owe tax, you'll pay:

• a late-filing penalty – You’ll pay 5% of the amount of tax you owe, plus 1% for every month that your return is late, for up to 12 months. That adds up to a maximum of 17% of the tax you owe.
• interest – You'll pay interest on the amount you owe beginning on May 1. You will also be charged interest on any late-filing penalties. Interest is compounded daily, not monthly or annually. The rate of interest charged by the Canada Revenue Agency (CRA) (called the prescribed interest rate) can change every 3 months.

If you file a late return more than once

The late-filing penalties are doubled. For example, if the CRA charged you late-filing penalties for any of the 3 previous years, you would pay a penalty of up to 50% made up of:

• 10% of the taxes you owe, plus
• 2% of the taxes you owe for each full month that your return is late, to a maximum of 20 months.

If you owe tax from previous years

The CRA will keep charging you interest compounded daily on those amounts. Any tax payments you make will be applied first to the tax owing from previous years.