Ontario's small business corporate income tax rate cut from 3.2% to 2.2%, effective July 1, 2026, is not a rate a Toronto-area CCPC simply starts using on its next return. For any corporation whose fiscal year does not end on June 30 or December 31, Bill 97, Plan to Protect Ontario Act (Budget Measures), 2026 — the 2026 Budget bill that received Royal Assent on March 26, 2026 — sets the lower small business deduction rate for "days in a taxation year after June 30, 2026," which requires the reduction to be prorated for taxation years straddling July 1, 2026: the old 3.2% rate applies to the portion of the year before the changeover, the new 2.2% rate applies to the portion on or after it, and the two are blended by the number of days in each period. That day-count rule is the part most bookkeeping software will not apply correctly on autopilot. This post works through the actual day-count mechanics for three common Toronto fiscal year-ends — December 31, March 31, and September 30 — with the dollar effect on a corporation earning at its small business limit, plus what the proration means for instalments already remitted and for the timing of owner remuneration.
Why this is a separate problem from "the rate is now 2.2%"
An earlier post on this change covered the headline numbers: 3.2% to 2.2%, effective July 1, 2026 under Bill 97, with the $500,000 Ontario small business limit unchanged, and the offsetting 2027 dividend tax credit adjustment. What that post did not do is walk through the arithmetic of a stub period — and that arithmetic is where the actual filing risk sits. A December 31 year-end corporation and a September 30 year-end corporation both file a single T2 for their 2026 fiscal year, both cite "the Ontario small business rate," and both are legally required to use a different blended rate on that return, because the number of days before and after July 1, 2026 in their respective years is different. If your accountant or software applies a flat 2.2% (or, worse, a flat 3.2%) to the whole fiscal year rather than the correct weighted-average, the T2 is calculated incorrectly regardless of which flat rate was used.
The mechanics: a weighted average by days in the year
The standard, long-established method Ontario and the CRA use to apply a mid-year corporate rate change is to weight each rate by the proportion of the tax year that falls on each side of the effective date:
Blended rate = (old rate × days before July 1, 2026) + (new rate × days on/after July 1, 2026), divided by total days in the tax year.
This is the mechanism the 2026 Budget Annex points to when it says the rate reduction "would be prorated for taxation years straddling July 1, 2026" — the government has not published a separate worksheet with the exact wording of the formula, so treat the day-count weighting below as the standard, conservative application of that proration principle rather than a quoted government formula, and confirm the final number with your T2 preparer.
Worked examples: three common Toronto fiscal year-ends
The table below assumes a corporation earning exactly $500,000 of active business income eligible for the small business rate in its 2026 fiscal year, to isolate the effect of the proration itself.
| Fiscal year-end | Fiscal year | Days at 3.2% (before Jul 1, 2026) | Days at 2.2% (on/after Jul 1, 2026) | Blended Ontario rate | Ontario tax on $500,000 | Tax at old flat 3.2% |
|---|---|---|---|---|---|---|
| December 31 | Jan 1 – Dec 31, 2026 | 181 | 184 | ≈2.70% | ≈$13,480 | $16,000 |
| March 31 | Apr 1, 2026 – Mar 31, 2027 | 91 | 274 | ≈2.45% | ≈$12,245 | $16,000 |
| September 30 | Oct 1, 2025 – Sep 30, 2026 | 273 | 92 | ≈2.95% | ≈$14,740 | $16,000 |
The pattern is straightforward once you see the day counts: a fiscal year that begins closer to July 1 and runs mostly after it (March 31 year-end) captures more of the year at the lower 2.2% rate and gets the largest reduction. A fiscal year that ends soon after July 1 but started long before it (September 30 year-end) captures more of the year at the old 3.2% rate and gets the smallest reduction. No Toronto CCPC in a straddling year gets the full-year benefit of 2.2% on its 2026 return — that only happens starting with the first full fiscal year that begins on or after July 1, 2026.
A note on the business limit: it did not change
Bill 97 changes only the rate, not the dollar threshold. The Ontario small business limit stays $500,000 — the same figure used in the worked table above. That $500,000 is not automatically yours alone: it is still shared among associated corporations (a group of related companies divides one $500,000 limit between them, however they choose to allocate it) and it still grinds down for a CCPC whose group had more than $10 million of taxable capital employed in Canada in the prior year, reaching zero at $15 million, and separately grinds down once the group's prior-year investment income passes $50,000, reaching zero at $150,000. Neither of those mechanics is new in 2026 — they simply did not change alongside the rate cut, and they matter more once the small business rate itself is worth less to preserve at 2.2% than it was at the old 3.2%. A private member's bill from 2025 (Bill 12, Cutting Taxes on Small Businesses Act) had proposed raising the limit to $600,000, but it did not proceed past First Reading and never became law — do not plan around it.
Instalments already remitted on the old assumption
If your 2026 corporate tax instalments were calculated using either a flat 3.2% or a flat 2.2% Ontario small business rate, they are almost certainly off by a few hundred to a few thousand dollars once the correct blended rate for your specific year-end is applied — the table above shows a swing of roughly $2,500 between the March 31 and September 30 scenarios alone at the same income level. This is not usually large enough to trigger instalment penalty concern on its own, but it is worth having your bookkeeper or accountant re-run the current-year instalment base once the correct blended rate for your fiscal year is confirmed, rather than catching the discrepancy for the first time when the T2 is filed. See our Ontario corporate tax guide for how Ontario CIT is calculated alongside the federal T2, and our corporate tax calculator to model the blended rate for your own year-end.
Remuneration timing and the 2027 dividend credit change
The proration works only in one direction — it lowers this year's corporate tax bill for the post-July-1 portion of a straddling year — but it interacts with a second, later change: Ontario's non-eligible dividend tax credit rate drops from 2.9863% to 1.9863% on January 1, 2027, to offset the lower corporate rate on the personal side. For a Toronto owner-manager weighing whether to declare a dividend before or after year-end, the corporate-side saving from the July 2026 proration is locked in regardless of when the dividend is paid, but the personal tax cost of drawing that income as a non-eligible dividend rises slightly for any dividend paid on or after January 1, 2027. If your fiscal year-end and your personal remuneration decisions both fall late in 2026, it is worth sequencing them with both changes in view rather than the corporate rate alone.
What Toronto-area business owners should do
- Identify whether your 2026 fiscal year straddles July 1, 2026. Only December 31 and June 30 year-ends avoid the proration entirely; every other year-end needs the blended rate.
- Ask your accountant for the specific day count, not an assumed flat rate — the difference between a correctly and incorrectly prorated Ontario small business rate on $500,000 of income can run into the thousands of dollars.
- Re-check current-year instalments against the corrected blended rate rather than waiting for the T2 filing to surface a discrepancy.
- Confirm your associated-corporation allocation of the $500,000 limit is still current — the limit itself did not change in 2026, but how a group divides it affects how much income actually gets the prorated rate.
- Sequence late-2026 dividend decisions with the January 2027 non-eligible dividend tax credit reduction in mind if your remuneration plan relies on dividends.
Key takeaways
- Ontario's small business rate cut to 2.2% is prorated by days for any tax year straddling July 1, 2026 — only calendar-year (December 31) corporations get a clean single-rate year.
- A December 31 year-end blends to roughly 2.70%, a March 31 year-end to roughly 2.45%, and a September 30 year-end to roughly 2.95% on $500,000 of eligible income — the exact figure depends on your specific day count.
- The $500,000 business limit did not change in 2026 — it remains shared among associated corporations and still grinds down under the taxable-capital and passive-income rules.
- Instalments calculated on a flat rate rather than the correct blend are likely off and worth re-checking before year-end.
- The corporate-side saving from the July 2026 proration is independent of the January 2027 dividend tax credit change, but the two are worth sequencing together for owner-manager remuneration.
If your fiscal year straddles July 1, 2026 and you need the correct blended Ontario small business rate confirmed for your instalments or your T2, RN Canada works with Toronto-area owner-managed corporations remotely from our Edmonton and Vancouver offices on exactly this kind of corporate tax planning.