The Canada Revenue Agency and various provincial bodies have set deadlines for the payment and filing of the various taxes, and the number of different deadlines can be overwhelming. Feel free to use this as a reference but note that this is for the most common deadlines and is not exhaustive:

Unlike personal taxes which are based on a calendar year, corporations are able to choose a year end. Each year, corporate income taxes must be paid based on the year’s taxable income. 

Filing Deadline: six month after the corporate year end.

Payment Deadline: Two months after the corporate year end. This is extended to three months if certain criteria are met. Smaller corporations generally qualify as long as the corporation and all corporations associated with it do not exceed the shared $500,000 business limit.

For example, if a corporation has a July 31, 2021 year end and did not use its full business limit in the prior year, the payment deadline would be October 31, 2021, and the corporate tax return would be due by January 31, 2022.

Note that once certain tax payable thresholds are passed, then the CRA and/or the provincial bodies may request monthly instalments.

A corporation also gets to choose its filing periods for GST/HST purposes. To keep everything simple, most choose the same period as their corporate year end. Once certain gross revenue numbers are passed, the corporation will be required to file more often.

Annual Filer (gross revenue under $1,500,000):

Filing and Payment Deadline: three months after the GST filing period

Quarterly Filer (gross revenue between $1,500,000 and $6,000,000):

Filing and Payment Deadline: one month after the GST filing period

Monthly Filer (gross revenue between $1,500,000 and $6,000,000):

Filing and Payment Deadline: one month after the GST filing period

Once GST payments pass a certain threshold, the CRA will require instalments otherwise they will charge interest.

Any corporation with employees must pay source deductions once certain thresholds are met. Unlike corporate taxes or GST, payroll is based on a calendar year.

Regular Remitters: Monthly remittances are due the 15th day of the following month.

Threshold 1 Accelerated Remitters (average monthly withholdings between $25,000 and $100,000): Two remittances a month.

• Pay period 1st to 15th of the month is due the 25th day of the same month
• Pay period 16th to the end of the month is due the 10th day of the following month

Threshold 2 Accelerated Remitters (average monthly withholdings over $100,000): Four remittances a month.

• Pay period 1st to 7th of the month is due the third working day after the 7th
• Pay period 8th to 14th of the month is due the third working day after the 14th
• Pay period 15th to 21st of the month is due the third working day after the 21st
• Pay period 22nd to end of the month is due the third working day after the last day of the month
  



T4:

T4 Slips (payroll) are due the last day of February after the calendar year

T5:

T5 Slips (dividends, interest, royalties, etc.) are due the last day of February after the calendar year

T4A:

T4 Slips (non-construction contractors, among others) are due the last day of February after the calendar year

T5018:

Information return for construction contractors. This is due six months after the corporate year end.

T1135:

Form T1135 is when the corporation has foreign holdings over $100,000, and it is due at the same time as the corporate tax return.