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The best way to prepare for tax season as a business owner is to close your books early and know which of your dates come first. If you’re a sole proprietor with a December year-end, the 2025 return was due June 15, 2026, but any tax owing was due April 30, 2026. That gap catches people every year.
What should be done before the year ends?
Most of the pain in tax season comes from records that were never kept up, not from the tax itself. Sit down once a month and match your bank and card statements to your sales and expenses. Ten minutes in October beats a weekend in April.
Sort every expense into a category as you go. Split personal and business spending at the moment you pay, not later. If you work from home, work out your business share of the space now, because the CRA wants a reasonable basis such as the size of your workspace against the size of the home. Our guide to claiming business expenses goes through what counts.
Keep the paper too. Receipts, invoices and statements should be somewhere you can find them in five minutes, whether that’s a folder or a scanned archive.
Which dates matter for a business?
The CRA lists these for the 2025 return. It hasn’t published the dates for the 2026 return, so treat the same days as likely rather than confirmed, and check the CRA page in the new year.
| Who | What | Date on the CRA 2026 deadlines page |
|---|---|---|
| Sole proprietor | File the return | June 15, 2026 |
| Sole proprietor | Pay any balance owing | April 30, 2026 |
| Individual instalments | Four payments | March 15, June 15, September 15, December 15 |
| Corporation | File the T2 | Six months after the tax year-end |
| Employer | File T4 and T4A slips | Last day of February |
| GST/HST, monthly or quarterly | File and pay | One month after the period ends |
| GST/HST, annual | File and pay | Three months after the year-end |
A corporation’s balance is generally due two months after year-end. Some Canadian-controlled private corporations get three months if they meet the CRA’s conditions. The CRA can charge penalties and interest on late returns, so pay attention to both dates. Our guide to business filing deadlines covers each date in more detail.
How much cash should you set aside?
Ask this before the year closes, because the answer decides if you face a bill you can’t pay. Take a sole proprietor in Ontario with $80,000 of net business income. The self-employed tax calculator shows $13,234 of income tax and $8,893 of CPP, for $22,126 in all. That’s 27.7% of the income, and you’d keep $57,874.
The tool leaves out GST/HST, EI and your business expenses, so use it on net income, after costs. If it looks big, remember that CPP is doing much of it: you pay both the employee and the employer half.
Now the corporate case. With $300,000 of taxable active business income in Ontario, the corporate tax calculator gives $35,088, about 11.7%. That rate is a blend we derived for a calendar 2026 year, because Ontario cut its small business rate part-way through, so read it as an estimate. It also assumes a Canadian-controlled private corporation and leaves out tax on money paid to owners.
If you’ll owe tax every year, look at instalments. The tax instalments calculator checks whether they apply to you and splits the year into four payments.
What goes wrong most often?
Three things. First, people confuse the filing date with the payment date. Second, they leave the accountant until the week of the deadline, when accountants are busiest. Third, they mix personal and business money for eleven months and try to untangle it in the twelfth.
A smaller mistake is forgetting that GST/HST has its own calendar. A monthly or quarterly registrant files a month after each period, no matter when the income tax return is due. And you must file the return even with no activity.
Should you hire someone? If you have employees, a corporation or foreign sales, probably yes, at least for the first year. A sole proprietor with a simple set of books can often manage. We can’t say what an accountant costs, since fees vary too much to state honestly.
Where the numbers come from
Dates are from the Canada Revenue Agency’s 2026 tax deadlines page for businesses and self-employed individuals, and its pages on corporation returns and GST/HST reporting. Tax amounts come from the calculators on this site, which use 2026 rates from federal and provincial sources. We couldn’t confirm the exact 2026 return dates, so check the CRA before you rely on them.
Frequently asked questions
When should a business owner start preparing for tax season?
Start well before year-end. Reconcile your accounts monthly, and use the last quarter to see what you'll owe so there are no surprises.
Is the June 15 date for self-employed people also the payment date?
No. For the 2025 return, a sole proprietor's filing date was June 15, 2026, but any balance owing was due April 30, 2026.
When does a corporation file its T2?
Within six months after the end of its tax year. The balance owing is generally due earlier, after two months, or three for some qualifying corporations.
Do I need an accountant?
Not always. A sole proprietor with clean books can often file alone, but employees, a corporation or complex sales make help worth having.
Are the 2026 return dates published?
Not yet. The dates here are the ones the CRA lists for the 2025 return, so check its page before you rely on them.
- Self-employed taxes in Canada: income, CPP and GST
How tax works when you are self-employed in Canada: reporting income and expenses, paying both halves of CPP, instalments and when to register for GST
Information only. This page is general information, not tax, legal or accounting advice. Tax-Services.ca is an independent publisher: we don't prepare or file tax returns or offer tax services, and we have no connection with the CRA, Revenu Québec, any government or any company named on this page. Check the figures that matter with an official source or a qualified professional.