Ontario small business tax deadlines, explained
Incorporated Ontario businesses juggle HST, payroll remittance, and corporate T2 deadlines through the year.
An incorporated Ontario business has several recurring deadlines: payroll source deductions, HST returns, and the annual T2 corporate tax return, plus WSIB and EHT reporting where they apply.
The rhythm
Source deductions are typically remitted monthly, HST on a schedule set by your filing frequency, and the T2 six months after your fiscal year-end — with any tax owing generally due earlier than the return. Missing dates means penalties and interest. The full set of dates is in the table below.
Never track them alone
With current books, these deadlines are handled for you rather than tracked on a wall calendar. See our small business tax calendar for the full picture.
The recurring deadlines, on one page
An incorporated Ontario business runs several calendars at once. These are the ones that carry penalties:
| Filing | When it is due |
|---|---|
| Payroll source deductions | For regular remitters, the 15th of the month after you paid the wages |
| T4 / T4A slips | To CRA and to the worker by the last day of February for the previous calendar year |
| HST return | Annual filers: three months after fiscal year-end. Quarterly and monthly filers: one month after the period ends |
| T2 corporate return | Six months after your fiscal year-end |
| Corporate tax balance | Generally two months after year-end — three months for many CCPCs claiming the small business deduction |
| EHT annual return | Generally March 15 for the prior calendar year, where EHT applies |
| T5018 (construction) | Six months after the end of your chosen reporting period |
Figures are the published 2026 amounts, verified August 2026. Federal and Ontario thresholds change annually — confirm the current year before relying on them.
The trap in the T2: filing and paying are different dates
The most expensive misunderstanding on this list is that the T2 is due six months after year-end but the money is generally due sooner — two months after year-end, or three for many Canadian-controlled private corporations claiming the small business deduction. A corporation that waits until the filing deadline to think about the balance has usually been accruing interest for months.
Instalments compound it: corporations with tax owing above a threshold generally have to pay monthly or quarterly instalments through the year rather than settling at the end, and instalment interest applies when they are missed or short. None of this is difficult when the books are current — the amounts are known in advance instead of discovered. Our small business tax calendar lays out the full year.
This is general information, not tax advice for your situation. Get started and a Canadian accountant will give you the answer for your business.
Common questions
When is my T2 due in Ontario?
Six months after your corporation's fiscal year-end, though any balance owing is generally due two to three months after year-end.
How often do I file HST?
It depends on your assigned filing frequency, which is usually annual, quarterly, or monthly based on your revenue.
When is the T2 corporate tax return due in Ontario?
Six months after your fiscal year-end — so a December 31 year-end means a June 30 filing deadline. The balance owing is generally due earlier: two months after year-end, or three months for many CCPCs claiming the small business deduction. Filing on time while paying late still triggers interest.
What happens if I miss a payroll remittance deadline?
CRA charges a graduated penalty on late source deductions, starting at 3% for amounts one to three days late and rising to 10%, with 20% for repeated failures made knowingly or through gross negligence, plus interest. Unremitted source deductions are trust funds and directors can be held personally liable, which makes this the deadline least worth testing.
Do I have to pay corporate tax instalments?
Generally yes, once your corporate tax owing passes CRA’s threshold — monthly or quarterly depending on your circumstances — rather than paying the whole balance after year-end. Instalment interest applies to payments that are missed or short even if the return itself is filed on time.