As the new financial year begins, Ontario businesses must stay on top of critical accounting and tax deadlines to remain compliant with the Canada Revenue Agency (CRA) and applicable provincial requirements. Whether you operate a corporation, sole proprietorship, or partnership in Ontario, understanding what to file and when is essential to avoid penalties and optimize tax planning.

This guide outlines the key accounting deadlines for Ontario businesses, explains who they apply to, and provides practical tips to help you stay compliant throughout the year.

Why Accounting Deadlines Matter for Ontario Businesses

Missing accounting and tax deadlines in Ontario can result in:

• CRA late-filing penalties and interest
• Cash-flow disruptions
• Increased CRA audit risk
• Loss of tax credits or deductions

Staying ahead of deadlines helps Ontario businesses:

• Improve financial forecasting
• Plan taxes efficiently
• Maintain clean, audit-ready records
• Focus on growth instead of compliance stress

Key Accounting and Tax Deadlines for Ontario Businesses

1. Corporate Income Tax (T2) Filing Deadline – Ontario Corporations

Deadline: 6 months after the fiscal year-end

• Applies to all Ontario corporations, including inactive corporations
• Example:
• Fiscal year-end: December 31, 2024
• T2 return due: June 30, 2025

⚠️ Important for Ontario corporations:

Any corporate income tax payable is generally due 2 or 3 months after year-end, depending on whether the corporation qualifies for the Small Business Deduction (SBD).

2. Sole Proprietorship & Partnership Tax Filing – Ontario

Filing Deadline: June 15

Tax Payment Deadline: April 30

• Applies to Ontario sole proprietors and partners
• Business income is reported on the T1 personal tax return
• Even though filing is due June 15, any balance owing must be paid by April 30 to avoid interest

3. Personal Income Tax Deadline – Ontario Residents

Deadline: April 30

• Applies to Ontario employees, retirees, and individuals with non-business income
• Each spouse or common-law partner must file separately

4. Payroll Deadlines (T4 & T5 Slips) – Ontario Employers

Deadline: February 28 of the following year

• T4 slips: Employment income
• T5 slips: Dividends and investment income
• Required for all Ontario employers and corporations

Late or incorrect payroll slips can trigger CRA penalties and payroll audits.

5. GST/HST Filing Deadlines – Ontario Businesses

Ontario businesses registered for HST (13%) must file based on their assigned reporting period:

Reporting Period

Filing Deadline

Monthly

1 month after period-end

Quarterly

1 month after quarter-end

Annual (Individuals)

June 15

Annual (Corporations)

3 months after fiscal year-end

📌 Reminder:

Any HST owing is usually due earlier than the filing deadline.

Best Practices for Ontario Businesses in the New Financial Year

• Confirm your fiscal year-end early
• Keep bookkeeping updated monthly
• Reconcile HST, payroll, and bank accounts regularly
• Track installment requirements
• Engage an Ontario CPA for proactive tax planning

How an Ontario CPA Can Help Your Business

A CPA licensed in Ontario can help you:

• Identify federal and provincial filing obligations
• Reduce CRA audit risk
• Optimize small business tax credits
• Manage payroll and HST compliance
• Stay aligned with CRA and Ontario tax rules

Frequently Asked Questions (FAQs)

What are the key accounting deadlines for Ontario businesses?

Key deadlines include:

• Corporate tax filing: 6 months after year-end
• Sole proprietors: June 15
• Personal tax: April 30
• T4/T5 slips: February 28
• HST: Varies by reporting period

Is the corporate tax deadline the same across Canada?

Yes, the T2 filing deadline is federal, but Ontario corporations must also account for provincial tax rates and credits.

Do Ontario sole proprietors get extra time to file taxes?

Yes. Ontario sole proprietors have until June 15 to file, but any taxes owing must be paid by April 30.

When are T4 and T5 slips due in Ontario?

Ontario employers must file T4 and T5 slips by February 28 of the following year.

Does HST filing differ in Ontario?

Ontario uses HST (13%), and filing deadlines depend on whether your reporting period is monthly, quarterly, or annually.

How can I avoid CRA penalties in Ontario?

You can avoid penalties by:

• Filing on time
• Paying taxes before due dates
• Keeping accurate records
• Working with a licensed Ontario CPA

Final Thoughts for Ontario Business Owners

Navigating the new financial year doesn’t have to be overwhelming. By understanding Ontario-specific accounting deadlines and planning ahead, businesses can remain compliant, reduce tax stress, and focus on long-term growth.

Need Help with Accounting or Tax Planning in Ontario?

Momentum Accounting CPA Professional Corporation helps Ontario businesses with bookkeeping, tax compliance, CRA correspondence, and proactive tax planning—so deadlines never catch you off guard.