Corporate tax deadlines in Canada: the dates that catch business owners out

Most business owners know their corporate tax return is due "six months after year end." Far fewer know that the money is due before the paperwork. That gap is where a large share of avoidable interest charges come from — not from anyone forgetting to file, but from assuming one deadline covers both obligations.

Here is how the corporate calendar actually works.

The filing deadline and the payment deadline are different

A T2 corporate income tax return is due six months after the end of your fiscal year. If your year end is 31 December, the return is due 30 June.

The balance owing is due earlier: generally two months after year end, extended to three months for many Canadian-controlled private corporations that meet the conditions for the small business deduction. So for a 31 December year end, the money can be due at the end of February or March while the return itself is not due until June.

The practical consequence: you often need a reasonable estimate of the year's tax before the return is finished. Interest runs from the payment deadline, not the filing deadline.

Instalments creep up on growing companies

Once a corporation's tax owing passes a modest threshold, the CRA expects it to pay throughout the year in monthly or quarterly instalments rather than in one lump at year end.

This catches profitable second and third years in particular. The first year there is nothing to instalment against, so nothing happens. The second year, instalments are expected based on the first year's results — and a company that has grown can find itself behind on payments it did not know were due, accruing interest quietly.

If your corporation was materially more profitable last year than the year before, it is worth checking whether you are now in instalment territory.

A nil return is still a return

A resident corporation has to file a T2 every tax year, including years where it was inactive or had no tax payable. Dormant holding companies and businesses that paused are the usual casualties here.

Skipping a nil return does not save anything and can complicate later filings, particularly if you later need to establish a history of losses or carry something forward.

The other filings that share the calendar

Corporate income tax is not the only deadline in the year:

• T4 and T4A information returns — due by the end of February for the preceding calendar year, regardless of your fiscal year end.
• T5 investment income slips — also tied to the calendar year, not your fiscal year.
• GST/HST returns — monthly, quarterly or annually depending on your assigned reporting period. This is separate from income tax and has its own filing and payment dates.
• T5018 contract payment reporting — for construction, due six months after the reporting period you have chosen.

The trap in this list is the mismatch: information returns follow the calendar year while your income tax return follows your fiscal year. A company with a June year end has obligations landing in February that have nothing to do with its year-end work.

What to actually do about it

Three things prevent almost all of the interest we see:

1. Write down your own dates. Six months, two or three months, and the February slip deadlines — for your specific year end, as actual dates rather than intervals.
2. Estimate before you finish. You do not need a completed return to make a payment against the balance. An informed estimate paid on time beats an exact figure paid late.
3. Check instalment status after a good year. Growth is when the requirement appears.

If you are not sure which of these apply to your corporation, that is a short conversation rather than a long engagement — and it is one worth having before a deadline rather than after.