Tax Deadlines Every Ontario Small Business Should Know in 2026

Running a business in Burlington means wearing a lot of hats — and “tax-deadline tracker” is rarely the one you enjoy. But missing a Canada Revenue Agency (CRA) due date is one of the most expensive mistakes a small business can make. Late filing alone can add 5% of your balance plus 1% for every month you’re late, on top of interest that compounds daily.

The good news: with the dates in front of you, staying onside is straightforward. Here are the 2026 CRA deadlines (for the 2025 tax year) that matter most to Ontario small business owners.

A quick note on weekends: when a CRA deadline lands on a Saturday, Sunday, or public holiday, it moves to the next business day. The dates below already reflect that.

Personal income tax deadlines

Even incorporated owners usually file a personal return, so start here.

• April 30, 2026 — File and pay your 2025 personal income tax return (for most individuals).

• June 15, 2026 — File your personal return if you (or your spouse/common-law partner) are self-employed. Important catch: any balance owing is still due April 30, 2026, even though you have until June to file.

If you pay tax by instalments, the personal instalment due dates are March 15, June 15, September 15, and December 15, 2026.

Corporate income tax (T2) deadlines

Your corporate dates depend on your fiscal year-end, not the calendar.

• Filing the T2 return: due within six months of your fiscal year-end. A December 31, 2025 year-end means a June 30, 2026 filing deadline.

• Paying the balance owing: generally due two months after year-end. Many Canadian-controlled private corporations (CCPCs) that qualify for the small business deduction get three months. For a December 31, 2025 year-end, that’s roughly February 28 / March 2, 2026 (two months) or March 31, 2026 (three months).

Because filing and payment can fall on different dates, this is one of the easiest places to get tripped up. When in doubt, confirm your specific dates with your accountant.

Payroll remittances

If you have employees, source deductions (CPP, EI, income tax) must reach the CRA on schedule.

• Regular remitters: remit by the 15th of the month following the month you made the deductions.

• T4 and T5 slips: must be issued to your team and filed with the CRA by March 2, 2026 (the last day of February falls on a weekend).

Payroll penalties can be steep and are charged on the full remittance, so this is not the place to be casual.

GST/HST deadlines

Your HST due date depends on how often you file:

• Monthly or quarterly filers: file and pay one month after the end of each reporting period.

• Annual filers (most incorporated businesses): file and pay three months after your fiscal year-end.

• Annual filers who are sole proprietors with a December 31 year-end: file by June 15, 2026 but pay any balance by April 30, 2026 — mirroring the self-employed personal deadlines.

A common Burlington small-business mistake is treating HST you’ve collected as cash flow. It isn’t — it’s money you’re holding for the CRA.

A few other dates worth a calendar reminder

• RRSP contributions for 2025: March 2, 2026.

• Partnership information return (where all partners are individuals): March 31, 2026.

• Tax instalments (personal): March 15, June 15, September 15, December 15, 2026.

What happens if you miss a deadline?

The CRA doesn’t send a friendly reminder — it sends a bill. Late filing typically costs 5% of the balance owing plus 1% per month (up to 12 months). For repeat late filers it can climb to 10% plus 2% per month. On top of that, interest compounds daily at the CRA’s prescribed rate (around 10% heading into 2026). A modest balance can balloon quickly.

The smarter — and cheaper — approach is simple: know your dates, set reminders a few weeks ahead, and keep your books current year-round so filing is a non-event.

Stay ahead of every deadline with Shandal CPA

We help Burlington, GTA, and Ontario business owners file on time, pay only what they owe, and plan ahead so tax season is never a scramble. If you’re not 100% sure of your own filing and payment dates — especially your corporate year-end and HST schedule — let’s map them out together.

Call us at (416) 526-5667 or request a consultation today.

This article is general information for Ontario small business owners and is current for the 2025 tax year (2026 filing season). It is not tax advice for your specific situation, and CRA dates can shift to the next business day on weekends and holidays. Please confirm your deadlines with Shandal CPA.