Mark Your Calendar: Corporate Tax Deadlines and Instalments – A Complete Guide by a Montreal CPA Firm Near You

Understanding corporate tax deadlines in Canada is essential for avoiding penalties,

interest, and CRA enforcement actions. Corporations face more complex tax obligations

than individuals, including multiple filing deadlines, instalment requirements, GST/QST

reporting periods, payroll remittances, T4/T5 filing deadlines, and provincial obligations.

Missing any of these corporate tax deadlines can create cascading financial

consequences—particularly interest on late payments, which compounds daily. Whether

your business is a startup, a growing corporation, or an established enterprise, knowing

the exact CRA due dates for corporate taxes is essential to maintaining compliance and

protecting cash flow. This guide provides a clear breakdown of every major corporate

tax deadline in Canada, how corporate instalments work, and how CRA applies

penalties when deadlines are missed.

Legal and Regulatory Framework

Corporate tax deadlines in Canada are governed by the Income Tax Act, the Excise Tax

Act (for GST/HST), Revenu Québec legislation, and payroll statutes. Key rules include:

• T2 Corporate Tax Return Deadline:

Every corporation must file its T2 return within six months after its fiscal year-end (ITA

section 150(1)).

Example: A year-end of December 31 means the T2 is due June 30.

• Corporate Tax Payment Deadline:

Taxes owing must be paid within two or three months after year-end:

– Two months for most corporations

– Three months for CCPCs with active business income and taxable income under the

small business limit

• Corporate Instalments:

Corporations expecting to owe more than $3,000 in federal corporate tax must make

monthly or quarterly instalments under section 157.

Instalments may be calculated by:

– the current-year method,

– the prior-year method, or

– the second prior-year method.

• GST/HST / QST Deadlines:

Monthly, quarterly, or annual depending on remitter status.

• Payroll Deadlines:

Source deductions must be remitted based on remitter type (regular, quarterly,

accelerated).

• T4/T5 Slips:

Due February 28 each year.

These statutory timelines form the foundation of corporate tax deadlines in Canada.

Key Court Decisions

Court decisions highlight CRA’s strict enforcement of corporate deadlines.

In McLarty v. Canada, CRA applied interest on late corporate instalments even though

the corporation ultimately had no balance owing. The court ruled that instalment interest

is statutory and unavoidable.

In Iberville Construction v. The Queen, a corporation missed its payment deadline due

to internal bookkeeping issues; the court upheld CRA’s penalties, confirming that

administrative errors do not excuse late filings.

In Revelstoke Credit Union v. Canada, the court confirmed that CRA is not obligated to

waive interest unless exceptional circumstances exist.

These rulings reinforce that corporations must meet all CRA due dates regardless of

internal challenges.

Why CRA Targets This Issue

CRA actively monitors corporate tax deadlines because timely filing and remittance are

central to the tax system. CRA flags corporations that:

• frequently file T2 returns late

• make late instalment payments

• show inconsistent GST/QST filings

• fail to remit payroll deductions on time

• miss T4/T5 deadlines

• repeatedly request relief for late filings

CRA views late payroll remittances as especially serious because they involve

employee trust funds. Frequent late filing may also trigger deeper audits. Understanding

corporate tax deadlines in Canada is critical to maintaining a clean compliance profile

with CRA.

Mackisen Strategy

At Mackisen CPA Montreal, we help corporations stay on top of all filing deadlines with

a structured compliance calendar. Our method includes:

• tracking all T2 corporate tax deadlines

• scheduling corporate tax payments before the two- or three-month deadline

• calculating instalments using the most advantageous method (current, prior, or second

prior year)

• reconciling GST/QST accounts and submitting filings on time

• managing payroll deduction remittances based on remitter type

• preparing and filing T4, T5, and RL slips before February 28

• ensuring provincial filings (including Québec CO-17 where applicable) are completed

• implementing year-round bookkeeping best practices to avoid last-minute issues

By maintaining a proactive schedule, we eliminate the risk of late filings and interest

charges.

Real Client Experience

A corporation repeatedly filed its T2 return late, triggering penalties and a CRA

compliance review. We implemented a corporate deadline calendar, streamlined their

bookkeeping, and restored full compliance.

Another client underestimated its corporate tax liability and missed several instalment

deadlines. CRA assessed instalment interest. We recalculated instalments using the

second prior-year method, reducing future payments.

A third business fell behind on payroll remittances during rapid expansion. CRA issued

late-remittance penalties. We restructured their payroll system and established

automated remittances to prevent repeat issues.

These examples demonstrate why corporations must manage their tax deadlines

strategically.

Common Questions

Corporations often ask whether filing extensions exist. T2 deadlines cannot be

extended.

Others ask whether instalment interest can be waived. CRA does so only under

extreme circumstances (financial hardship, CRA error).

Some ask whether GST/HST and payroll remittances are part of T2 filing. They are

separate obligations with separate deadlines.

Another question: Can a corporation file before year-end? No—returns must follow the

fiscal year.

These questions highlight the importance of understanding corporate tax deadlines in

Canada.

Why Mackisen

With more than 35 years of combined CPA experience, Mackisen CPA Montreal

ensures corporations meet every CRA deadline accurately and on time. Whether your

business needs calendar planning, instalment strategies, payroll compliance, or full

corporate tax filing support, our team delivers precision, transparency, and protection

from audit risk.