For Alberta corporations, January 1 is not just the start of a new year, it is the opening of one of the most deadline-intensive periods on the corporate compliance calendar. Miss the wrong date and your corporation faces CRA interest charges, late-filing penalties, and potential disruption to credit facilities that rely on clean financial statements.
This guide consolidates every material corporate tax and compliance deadline your Alberta corporation should have on the calendar in 2026, specifically tailored for companies with a calendar year-end of December 31, 2025, with notes on the rules that apply specifically to corporations operating in Alberta..
This post provides general information only and does not constitute tax advice for your specific situation. Deadlines can vary based on your corporation’s fiscal year-end, industry, and filing history. Consult a qualified CPA for advice tailored to your circumstances.
T2 and AT1 Corporate Income Tax Returns
Unlike most other provinces, Alberta self-administers its own corporate income taxes. Every Alberta-incorporated company must file two completely separate corporate tax returns for each taxation year:
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- Federal T2 Return: Filed with the Canada Revenue Agency (CRA).
- Alberta AT1 Return: Filed directly with the Alberta Tax and Revenue Administration (TRA).
Both the T2 and AT1 returns must be filed no later than six months after your corporate fiscal year-end. For corporations with a standard calendar year-end (December 31, 2025), the strict filing deadline for both returns is June 30, 2026.
Filing late, even by a single day, triggers a 5% penalty on any unpaid balance, plus an additional 1% per month for up to 12 months. A second late filing within three years doubles these percentages to a 10% upfront penalty and 2% per month.
Corporate Tax Instalment Deadlines
Alberta corporations that expect to owe more than $3,000 in total corporate tax are required to make instalment payments throughout the year. By default, instalments are due monthly. Your corporation only qualifies for a quarterly schedule if it is a CCPC with taxable income of $500,000 or less and taxable capital of $10 million or less.
GST/HST Filing Deadlines
Most Alberta corporations are registered for GST (Alberta has no PST). Your filing frequency is determined by your annual taxable supplies.
Refers to the total worldwide sales or revenues your business generates from selling goods and services that are subject to GST (including those taxed at 5% and those that are “zero-rated” or taxed at 0%, such as exports or basic groceries). It does not include revenues from exempt supplies (like residential rent or certain financial services), nor does it include capital asset sales. Essentially, it is a measure of your business’s gross eligible sales volume.
For a December 31 fiscal year-end, the 2026 GST deadlines for quarterly filers are: April 30, July 31, October 31, and January 31, 2027.
Many Alberta corporations claim Input Tax Credits (ITCs) without holding a valid supplier invoice. For expenses over $30, the invoice must display the supplier’s 9-digit GST number. For expenses over $150, it must also name your corporation. Credit card slips alone are not valid audit proof.
Payroll Remittance and T4 Deadlines
If your Alberta corporation has employees, two separate payroll compliance streams apply: remittances throughout the year, and T4 information returns at year-end.
If a remittance deadline falls on a Saturday, Sunday, or a CRA-recognized public holiday, the deadline automatically extends to the next business day.
T4 slips and the T4 Summary must be filed with CRA and distributed to all employees by the last day of February. For 2025 payroll, because February 28, 2026 is a Saturday, this deadline extends to March 2, 2026.
Workers’ Compensation Board (WCB) Alberta
If your corporation hires workers or certain subcontractors in Alberta, you must register with WCB-Alberta and pay premiums based on your insurable earnings. WCB assessments are entirely separate from your CRA payroll remittances and are administered directly by the province.
- WCB Assessment Payments: WCB-Alberta will issue a Statement of Account based on your premium schedule. Payments are due in full within 30 days of the statement date (outstanding balances face a 1.5% monthly service charge).
- Annual Payroll Report: You must file an annual return by February 28 each year. Because February 28, 2026 is a Saturday, you must submit your documentation by March 2, 2026. This return reports your actual assessable employee earnings from the prior calendar year and provides your estimated payroll for the current year.
- Clearance Certificates: You should request a clearance certificate from the WCB website before hiring any contractor or subcontractor to work on your premises. If you fail to get a clearance certificate and the contractor hasn’t paid their WCB premiums, your corporation can be held legally liable for their unpaid balance.
If a subcontractor is injured on your job site and does not have active WCB coverage, WCB will look to your corporation to cover the costs. Checking for a clearance certificate before they step foot on your site protects you from inheriting someone else’s workplace liability.
At-a-Glance: 2026 Alberta Corporate Deadline Calendar
What Happens When You Miss a Deadline?
The tax authorities do not automatically waive interest and penalties for first-time or inadvertent late filings. While you can apply for penalty and interest relief through the CRA Taxpayer Relief Provisions under subsection 220(3.1) of the Income Tax Act, relief is highly discretionary, takes months to process, and is rarely guaranteed.
The single most effective strategy is implementing a proactive compliance calendar managed by your accountant throughout the year, with reminders built into your corporate accounting workflow well in advance of each due date.
The cost of proactive compliance planning is always lower than the penalties and interest required to correct a missed deadline. A corporate compliance calendar is one of the highest-return investments an Alberta corporation can make.
Need a CPA Team that Manages Every Deadline for You?
Our Calgary CPA team works with Alberta corporations of all sizes to build compliance calendars, manage quarterly instalment calculations, prepare both federal T2 and Alberta AT1 returns, and ensure payroll obligations are met accurately and on time.
Staying on top of every corporate deadline is easier with a dedicated CPA team in your corner. Book a meeting with us to discuss how we can support your 2026 tax compliance calendar.
