Markham Small Business Tax Deadlines 2026: The Complete Calendar

Page summary

A practical calendar of every 2026 tax deadline Markham small businesses need to know: T1 and T2 filing, quarterly instalments, HST, payroll remittances, and the penalties for missing each one.

• Article details: Tax Tips; published May 10, 2026; 10 min read.
• Most Markham small business owners know taxes are complicated. What many underestimate is how much the timing matters. A perfectly accurate return filed one day late costs real money. A missed payroll remittance can trigger penalties larger than the remittance itself. And missing a balance-owing date — even when you intend to file the return on time — starts a compounding interest clock that runs daily.
• This guide is a single-reference calendar for every major 2026 CRA deadline that affects Markham small business owners: sole proprietors, incorporated businesses, HST registrants, and employers with payroll. Bookmark it, share it with your bookkeeper, and review it at the start of every quarter.
• If you want a CPA to manage these deadlines for you so none of them become a problem, our Markham accounting team works with small business owners year-round.
• Whether you need help with personal tax filing, corporate tax planning, or payroll and bookkeeping compliance, we handle the compliance calendar so you can focus on running your business.
• Contact us today to schedule a consultation, or explore our Markham accounting services to see how we work with small business owners year-round.

Related pages

• Blog: Browse more Canadian tax and accounting articles.
• Tax Planning & Advisory: Get advice before tax decisions become filing problems.
• Contact ARMalik: Ask a Markham CPA about how this topic applies to your situation.

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