Mississauga Tax Deadlines Every Small Business Owner Needs to Know

If you’re a small business owner in Mississauga, there’s one thing you definitely don’t want to mess around with—tax deadlines. We get it. Running a business means juggling a hundred things at once. But if there’s one thing that can sneak up on you and cause serious headaches, it’s forgetting when your taxes are due.
Don’t worry—we’ve got your back. Let’s walk through what deadlines really matter, what happens if you’re late, and how a good local accountant (hi, that’s us!) can save your business from stress and penalties.
Why Do Deadlines Matter, Anyway?
Deadlines might seem like just another date on the calendar, but in the world of taxes, missing one can cost you big. We’re talking late fees, interest, audits, and even frozen bank accounts if things really go off the rails.
Plus, staying on top of your tax deadlines means you can manage your cash flow better, plan ahead, and keep things running smoothly all year long.
Key Tax Dates You Should Know
Here’s the breakdown of dates to circle on your calendar:
1. Corporate Tax Filing
Due: 6 months after your fiscal year-end
If your year ends on Dec 31st? Your return is due by June 30.
But heads-up: your tax payment is due 2 months after year-end, so by Feb 28, not June.
2. HST Returns
If you’re a quarterly filer: usually 1 month after each quarter ends
If you file annually: it’s due 3 months after fiscal year-end
So if you’re annual with a Dec 31 year-end? File HST by March 31.
3. Payroll Remittances
Monthly? Due by the 15th of the next month
Accelerated schedule (if payroll > $25,000): might be semi-monthly
4. T4 & T5 Slips
These slips are due to employees and the CRA by February 28
What Happens If You File Late?
Let’s just say… it’s not great.
Late filing penalties: Usually 5% of what you owe, plus 1% for each month late (up to 12 months)
Interest charges on top of that
Delays on refunds or credits (especially HST or payroll)
Increased chance of audit (yup, they notice when you’re late)
Bottom line: late filing costs you money and stress. You don’t need that.
Why a Local Accountant Makes All the Difference
Sure, you could Google everything and try to do it yourself—but do you really want to?
Having someone who actually understands Mississauga’s business landscape, speaks your language (tax and otherwise), and keeps you ahead of deadlines? That’s a game-changer.
At M7, we help business owners all over the GTA stay organized, save on taxes, and grow smarter. We’ll remind you of deadlines, do the filings, and make sure you’re never left scrambling at the last minute.
Let’s Make Mississauga Accounting Work for You
Deadlines don’t have to be scary—or stressful. With the right accounting support in Mississauga, they just become another part of running your business like a professional. And when you’ve got someone watching your back, you can stay focused on growth instead of paperwork.
At M7, we know what it’s like to juggle a growing business in a fast-paced environment. Whether you’re a solo entrepreneur, a family-owned shop, or a company with employees and expansion plans, our mission is simple: take the tax and bookkeeping stress off your plate.
We’re not just a generic online service—we’re local, we know Mississauga’s business landscape, and we’ve helped hundreds of businesses stay organized, compliant, and profitable. Our team handles everything from corporate tax filings to HST, payroll, and financial reporting, so you never have to worry about missing a key deadline again.
If you’re still sorting through shoeboxes full of receipts, relying on outdated spreadsheets, or scrambling at tax time every year—let’s fix that. We’ll set up a system that actually works for your business, whether you’re just starting out or getting ready to scale past 7 figures.
Have questions about your next deadline? Want to make sure your books are in order before tax season hits? Let’s talk.
Book a free consultation today and discover how simple accounting in Mississauga can be—with the right team on your side.