Corporate Tax Filing Ontario: Deadlines, Rates, and Key Tips
- October 16, 2026
- Posted by: Taxmetic
- Category: Corporate Tax
For incorporated business owners across the Greater Toronto Area and Ontario, corporate tax filing follows the same federal rules as everywhere in Canada, but the consequences of getting it wrong are felt locally: interest charges, lost deductions, and cash flow surprises that a small business can ill afford. This guide explains the T2 filing deadline in Canada, what you actually pay under the Ontario small business tax rate, and the mistakes GTA and Ontario SMEs make most often.
Corporate Tax Filing in Ontario: The Deadlines That Matter
Every corporation in Canada must file a T2 corporate income tax return each year, even in a year with no income. The deadline is not April 30. It is tied to your corporation’s own fiscal year-end, which is why so many owner-managers get caught out.
The T2 filing deadline in Canada: six months after your fiscal year-end
The Canada Revenue Agency requires the T2 return within six months of the end of the corporation’s tax year. A December 31 year-end means a June 30 filing deadline. A March 31 year-end means September 30. If the deadline falls on a Saturday, Sunday, or a public holiday the CRA recognizes, the return is on time if received or postmarked by the next business day.
Filing late is expensive when tax is owing. The Income Tax Act sets the late-filing penalty at 5% of the unpaid tax plus 1% for each full month the return is late, up to 12 months. A corporation with no balance owing still has to file, and refunds are lost if the return goes in more than three years after the end of the tax year.
The payment deadline comes first: two months, or three for eligible CCPCs
Here is the trap. The payment deadline is earlier than the filing deadline. Any balance owing is generally due two months after the corporation’s year-end. A Canadian-controlled private corporation that claimed the small business deduction, and whose taxable income stayed within its business limit alone or together with associated corporations, generally gets three months.
Interest runs from the balance-due date, not the filing date. A corporation can file its T2 perfectly on time and still owe interest because the payment arrived late. This single misunderstanding is behind a large share of the interest charges we see on new client files.
Key Corporate Tax Deadlines at a Glance
| Obligation | Deadline |
|---|---|
| T2 return filing | 6 months after the corporation’s fiscal year-end (for example, June 30 for a December 31 year-end) |
| Balance of tax owing | 2 months after year-end; 3 months for an eligible Canadian-controlled private corporation claiming the small business deduction |
| Instalments | Monthly once tax exceeds $3,000; quarterly for eligible small Canadian-controlled private corporations |
| T4 slips and T4 Summary | Last day of February |
| Deadline to claim a refund | T2 must be filed within 3 years of the end of the tax year |
Ontario Small Business Tax Rates: What You Actually Pay
A qualifying Canadian-controlled private corporation pays a federal rate of 9% on its first $500,000 of active business income. The provincial layer sits on top of that, and Ontario changed it this year.
Effective July 1, 2026, Ontario reduced its small business corporate income tax rate from 3.2% to 2.2%. Combined with the unchanged 9% federal rate, the combined Ontario small business rate is now 11.2%, down from 12.2% before July 1, 2026. For a corporation whose tax year straddles that date, the Ontario portion is prorated, producing a blended rate for the transitional year. At the full $500,000 limit, the one percentage point cut is worth up to $5,000 a year in provincial tax.
Income above the small business limit is taxed at the general rate: 15% federal plus 11.5% Ontario, for a combined 26.5%. The gap between 11.2% and 26.5% is why protecting access to the small business deduction is the centrepiece of year-end planning.
Ontario Corporate Tax Rates at a Glance
| Income type | Federal | Ontario | Combined |
|---|---|---|---|
| Small business income (first $500,000 of active business income, qualifying CCPC) | 9% | 2.2% (from July 1, 2026; was 3.2%) | 11.2% (was 12.2%) |
| General rate (income above the limit) | 15% | 11.5% | 26.5% |
For tax years straddling July 1, 2026, the Ontario small business rate is prorated, producing a blended rate for the transitional year.
What Ontario SMEs Miss Most Often
1. Treating the filing deadline as the payment deadline. As above, the money is due months before the paperwork. Mark both dates, not one.
2. Skipping instalments. Corporations generally have to pay income tax in monthly instalments once total tax exceeds $3,000. Eligible small Canadian-controlled private corporations can pay quarterly instead. Missed or short instalments attract interest, and the bill arrives as a surprise because the CRA does not always send a reminder in the first year the obligation arises.
3. Letting passive income shrink the small business limit. The federal $500,000 limit is ground down when adjusted aggregate investment income exceeds $50,000 across the corporation and its associated corporations, at a rate of $5 of limit lost for every $1 over $50,000. Owners who retain profits inside the corporation and invest them often discover this only at filing time. One useful nuance: Ontario does not parallel this federal grind, so the provincial limit is unaffected.
4. Missing the 179-day bonus window. An accrued bonus to an owner-manager is deductible in the year only if it is paid within 179 days of year-end. Under subsection 78(4) of the Income Tax Act, salary or wages still unpaid 180 days after year-end are deemed not to have been incurred in that year, with payment on the 180th day treated as within the limit. Declare the bonus before year-end, then pay it inside the window, or the deduction moves to the following year.
5. Leaving salary-versus-dividend decisions until after year-end. Ontario’s 2026 Budget (Bill 97, which received Royal Assent on May 4, 2026) reduces the non-eligible dividend tax credit rate from 2.9863% to 1.9863% effective January 1, 2027, raising the personal tax cost of dividends paid from small business income. Whether salary or dividends leave more in your pocket depends on your bracket, your RRSP room, and your cash needs, but the analysis has to happen before December 31, not in April.
6. Assuming each corporation gets its own $500,000. Associated corporations, for example an operating company and a holding company under common control, share a single $500,000 business limit. Owners who incorporate a second company sometimes plan around a limit they do not have.
When a Corporate Tax Accountant in Ontario Earns Their Fee
The value of a corporate tax accountant in Ontario is not the return itself. It is the planning that happens before the year closes: choosing the right fiscal year-end, setting the salary and dividend mix, timing bonuses and capital purchases, and keeping books clean enough that the return reflects reality. By the time the T2 is being prepared, most of the important decisions are already made or already missed.
If your books are behind, your year-end is approaching, or you are unsure which of the deadlines above apply to you, get advice before the window closes.
Get your corporate tax filing right the first time. Book a free, no-obligation consultation with Taxmetic. We will review your deadlines, your rate position, and your year-end options, and tell you plainly what needs attention. Call +1 437 966 0033, email info@taxmetic.com, or book through our website.
This article is for informational purposes only and does not constitute professional tax or financial advice. Please consult a qualified accountant for advice specific to your situation.