Corporate Tax Deadlines and Instalments in Canada: The Calendar That Costs Money

The most expensive thing about corporate tax deadlines in Canada is that filing and paying are two different dates, and the payment one comes first.

Owners learn this the hard way. The return is not due for six months, so nothing feels urgent, and by the time it is prepared, interest has been accruing for four months on a balance nobody knew was owing.

The two dates, and why they differ

Filing: six months after your fiscal year end. A December 31 year end means the T2 is due June 30. The CRA’s rule is at when to file your corporation income tax return.

Payment: two or three months after your fiscal year end.

The balance of tax owing is generally due two months after year end. It extends to three months for a Canadian-controlled private corporation that claimed the small business deduction, subject to conditions on taxable income in the current and preceding year.

So for a December 31 year end, a typical CCPC pays by March 31 and files by June 30. Three months separate them, and the gap is where interest accumulates.

You must file a return even with no tax payable, and even with no activity. A dormant corporation still files. This surprises people who assume an inactive company has no obligations.

A December 31 year end, in order

The two bolded payment dates land three months before the filing deadline. That gap is where interest quietly accumulates.

What it costs to be late

Late filing penalty: 5% of the unpaid tax at the due date, plus 1% for each complete month the return is late, to a maximum of 12 months.

Repeat offender penalty: if the CRA issued a demand to file and you were charged a late-filing penalty in any of the three preceding tax years, the penalty rises to 10% plus 2% per month for up to 20 months.

Interest compounds daily on unpaid amounts at the prescribed rate, from the payment due date. Critically, interest charged by the CRA is not deductible, so the real cost is higher than the rate suggests.

The full schedule is at interest and penalties for corporations.

File on time even if you cannot pay. The late-filing penalty is calculated on unpaid tax and is entirely separate from interest. Filing on time and paying late costs interest. Filing late and paying late costs interest and a penalty that starts at 5%. Never delay the return because the money is not there.

Instalments: when the year becomes quarterly

Once your corporation’s tax owing passes a threshold, you stop paying annually and start paying through the year.

The general rule: a corporation must pay monthly instalments where total tax payable exceeds the threshold in either the current or preceding year. Eligible CCPCs meeting specific conditions, including claiming the small business deduction and staying within taxable income and capital limits, may pay quarterly instead.

There are three permitted calculation methods:

1. Current-year estimate. Base instalments on what you expect to owe this year. Lowest cash outlay if your estimate is good; interest applies if you underestimate.
2. Prior-year method. Base them on last year’s tax. Safe and simple.
3. Combination method. First instalment on the year before last, remainder on last year.

The CRA sets out the mechanics under corporation instalment requirements.

In a growth year, the prior-year method is usually right. Your instalments are based on a smaller number, and the balance is settled at year end. In a declining year, the current-year estimate avoids lending the government money you will only get back months later.

Instalment interest is charged when payments are late or short, and it can be offset by paying other instalments early. There is also a separate instalment penalty where instalment interest exceeds a threshold, worth knowing about because it is levied on top of the interest.

The first year is genuinely easier

A corporation in its first tax year generally has no instalment obligation, because instalments are calculated by reference to a preceding year that does not exist.

That relief is a trap in year two. The first year produces a tax bill, and suddenly the second year carries both a balance and an instalment schedule. Owners who spent the first year’s profit are now funding two obligations at once.

If your corporation is in its first year, set money aside on the assumption that year two will require both.

The other deadlines that share the calendar

Corporate income tax is one of four schedules running simultaneously.

Payroll source deductions. If you pay yourself or anyone else a salary, remittances are due on a schedule determined by your average monthly withholding: typically the 15th of the following month for new and smaller employers. Penalties here are steep: a percentage of the full remittance amount, not the shortfall, escalating with how late it is. See payroll remittance due dates. This is one of the practical costs to weigh in salary vs dividends.

T4 slips. Due to both the CRA and your employees by the last day of February for the preceding calendar year.

T5 slips for dividends. Same end-of-February deadline.

GST/HST returns. On their own frequency, which does not align with your fiscal year end. Covered in GST/HST registration.

Choosing a fiscal year end

A new corporation may choose any fiscal year end within 53 weeks of incorporation. Once chosen, changing it requires CRA approval.

Considerations that actually matter:

• A December 31 year end aligns with personal tax and with T4/T5 slips. Simplest to administer, but it concentrates everything into the same months.
• A non-calendar year end can smooth workload and can create planning room for owner compensation timing, since a bonus accrued in the corporation can be paid to you within a period after year end and land in a different personal tax year.
• Seasonal businesses often benefit from a year end after the busy season, when inventory is low and the picture is clearest.

Do not choose it casually and do not choose it to defer one year’s tax: the deferral is temporary and the administrative consequence is permanent.

Making the calendar work

The mechanism is unglamorous and it is the only thing that reliably works: Put every date in a calendar with a reminder two weeks ahead, at the point you incorporate. Filing date, payment date, instalment dates, remittance dates, slip deadlines.

Hold tax money separately. A second bank account, funded monthly with an estimate of corporate tax and any payroll remittances. Money in the operating account gets spent.

Reconcile monthly so the year-end number is not a surprise. The routine is in the monthly close.

Estimate your corporate tax quarterly, not annually. A rough number in month three is worth more than an exact one in month fourteen.

If you are already behind

File first. Immediately. The late-filing penalty stops growing the day the return is filed, and it is the largest single component of what you owe.

Then pay what you can: interest is charged on the outstanding balance, so partial payment reduces it. The CRA will discuss payment arrangements, and it is a substantially better conversation to have before collections activity begins than after.

If penalties or interest arose from circumstances genuinely beyond your control, serious illness, a natural disaster, or CRA error, taxpayer relief may be available. It is discretionary, it applies to penalties and interest rather than the tax itself, and it requires a written request with supporting facts.

If your corporate deadlines have gotten away from you, dealing with it deliberately is considerably cheaper than another quarter of compounding.