The Second Corporate Return Every Alberta Company Files: A Plain Guide to the AT1

2026-10-16 · RKube Services

Alberta corporations file a second return, the AT1, alongside the federal T2. Who files, the 2% and 8% rates, mandatory net file, instalment rules and the November 14, 2026 TRACS change.

If you incorporate anywhere else in Canada except Quebec, you file one corporate income tax return: the federal T2, which also covers your provincial tax. Alberta is different. A corporation with a permanent establishment in Alberta files the T2 with the Canada Revenue Agency (CRA) and a second return, the AT1, with Alberta Tax and Revenue Administration (TRA). Same year, same income, two returns, two balance-due calculations.

Owners of small Calgary and Edmonton corporations often find this out the hard way, when a TRA notice arrives for a return they didn't know existed. This guide covers who files the AT1, the 2% and 8% Alberta rates, the rule that now requires every regular corporation to file the AT1 electronically, the instalment and payment dates (including the rule that lets most small CCPCs skip Alberta instalments entirely), and two TRA account changes landing in 2026. It's written for owners of small incorporated businesses in Alberta.

Sources: the Government of Alberta's corporate income tax page and tax, levy and prescribed interest rates page, plus the CRA's pages on the T2 balance-due day and instalment requirements, all read in October 2026.

Two returns, one year

For both returns, a corporation with a December 31, 2025 year end files by June 30, 2026, and one with a December 31, 2026 year end files by June 30, 2027.

Who has to file an AT1

Alberta's rule is simple: a corporation with a permanent establishment in Alberta at any time during the taxation year must file an AT1. That includes corporations incorporated in Alberta and corporations formed in another province or country that are registered to do business in Alberta. The definition of a permanent establishment and the exemptions are in TRA's Information Circular CT-2, Filing and Payment Requirements.

What doesn't matter: whether you had income, whether you owe tax, or how small you are. A holding company with no activity still files.

Your Corporate Account Number (CAN)

To file, you need an Alberta Corporate Account Number. For an Alberta corporation, the CAN is the same number as the Corporate Access Number on your Alberta Certificate of Incorporation. A corporation formed outside Alberta gets one when it registers to do business in the province. Keep it handy, because net file won't accept an AT1 without a valid CAN.

The Alberta rates: 2% and 8%

Alberta's corporate rates have been the same since July 1, 2020:

• Small business rate: 2% on active business income eligible for the Alberta small business deduction, up to a $500,000 business limit.
• General rate: 8% on income above that and on income that doesn't qualify for the small business deduction.

Alberta doesn't have a provincial sales tax either, so most Alberta businesses only deal with the 5% GST on the sales side.

Worked example: a Calgary CCPC

Say a Calgary, AB consulting corporation, a Canadian-controlled private corporation (CCPC), has $620,000 of active business income for tax year 2026 and claims the small business deduction on the first $500,000.

That $19,600 goes on the AT1 and is paid to TRA. The federal tax goes on the T2 and is paid to the CRA. They're separate accounts, so a payment to one doesn't cover the other. If you send your whole corporate tax payment to the CRA, the Alberta balance is still unpaid, and Alberta charges daily compound interest on late payments.

The business limit can be reduced or shared for associated corporations, and some income (like investment income) is taxed differently, so treat this as an illustration of how the two rates stack, not a full calculation.

Net file is now mandatory for almost everyone

This is the change that catches small corporations. Alberta used to let corporations with gross revenue of $1 million or less file a paper AT1. That exception is gone. For taxation years beginning after December 31, 2024, every corporation must file its AT1 and all schedules electronically through TRA's net file service, except:

• insurance corporations
• non-resident corporations
• corporations reporting in a functional currency
• corporations exempt from tax under section 35 of the Alberta Corporate Tax Act

The penalty for a corporation that should have net filed and didn't is $1,000. Tax preparers who are paid to prepare more than 5 AT1s in a calendar year must also net file, or face a $100 penalty per return.

How net file works:

• You need AT1 certified software. No access code or registration is required to send it.
• You get an immediate receipt confirmation, which is your proof of filing.
• It's available Monday to Saturday from 7 am to midnight MST, and Sunday from 5:30 pm to midnight MST.
• Amended AT1s can be net filed too.

An AT1 counts as filed on the date TRA receives it.

When Alberta tax is due: instalments and the balance-due day

Alberta's general rule: corporate tax is paid in equal monthly instalments by the last day of each month in the taxation year, with any balance due by the end of the second month after year end. If a due date falls on a weekend or holiday, it moves to the next business day.

Then come the exemptions, and most small corporations fit one of them.

Small CCPCs pay no Alberta instalments and get three months. A CCPC doesn't have to pay Alberta instalments during the year, and can pay its full Alberta tax by the end of the third month after year end, if it meets any one of these:

• it claims the Alberta small business deduction and has taxable income of $500,000 or less in the current year, or
• it claimed the Alberta small business deduction and had taxable income of $500,000 or less in the previous year, or
• its Alberta tax for the current year, or its first instalment base, is $2,000 or less.

Other corporations with $2,000 or less of Alberta tax also skip instalments, but pay by the end of the second month.

New corporations (other than ones formed by amalgamation) don't pay instalments in their first taxation year and pay by the end of the second month.

Don't mix this up with the federal rules

The federal T2 has its own payment rules, and they're stricter for some of the same companies. Federally, a corporation generally gets three months to pay only if it was a CCPC throughout the year, claimed the small business deduction in the current or prior year and its taxable income (including associated corporations) for the previous year didn't exceed its business limit. Federal instalments apply once tax for the year or the prior year is over $3,000.

So a small Calgary, AB CCPC with a December 31, 2026 year end might pay no Alberta instalments at all and owe its Alberta balance by March 31, 2027, while still owing federal instalments during 2026. Two schedules, two payment accounts.

Two TRA account changes in 2026

Both of these affect how you see and manage your Alberta corporate tax account in TRA Client Self-Service (TRACS).

Online mail is now the default (since April 1, 2026). TRA sends corporate income tax correspondence through online mail in TRACS by default for all new corporations incorporated with Alberta Corporate Registry, existing corporations that have a TRACS account, and corporations that have given access to a third party like an accounting firm or bookkeeper. If nobody's checking TRACS, you can miss a notice.

New TRACS enrolment rules from November 14, 2026. TRA is ending the current PIN request process for corporate income tax accounts. After the change:

• The account owner must be a listed director of the corporation, with a verified Alberta.ca account (Alberta residents) or a completed Interac Document Verification Service check (directors without Alberta government ID).
• TRACS validates both conditions at every login. If either fails, the account owner loses access until it passes.
• Account owners can delegate the account representative role to someone else, such as a bookkeeper or accountant. Representatives can keep using a basic Alberta.ca account.
• If the current account owner isn't a listed director on November 14, 2026, their access is changed to account representative.

What to do before November 14: verify your Alberta.ca account, check that your director information in Alberta Corporate Registry is current, and make sure your name matches exactly in both places. If your bookkeeper or accountant currently holds owner access, a director should take over as owner and delegate representative access back to them.

AT1 checklist for Alberta corporations

1. Confirm you have a CAN and that it's on file with your accountant.
2. Diary both deadlines: T2 and AT1, each 6 months after year end.
3. Make sure your AT1 is prepared in certified software and net filed, not mailed.
4. Check whether you qualify for the CCPC no-instalment rule for Alberta, separately from the federal rules.
5. Pay Alberta tax to TRA and federal tax to the CRA, never one payment for both.
6. Check TRACS online mail regularly.
7. Before November 14, 2026, verify the director's Alberta.ca account and fix any name mismatch with Corporate Registry.

Questions Alberta business owners ask

Do Alberta corporations file a separate provincial tax return? Yes. Any corporation with a permanent establishment in Alberta during the year files an AT1 with Alberta TRA, in addition to the federal T2 with the CRA.

When is the Alberta AT1 due? Within 6 months after the end of the corporation's taxation year, the same as the T2. For a December 31, 2026 year end, that's June 30, 2027.

What is the Alberta small business tax rate? 2% on income eligible for the Alberta small business deduction, up to $500,000. The general Alberta rate is 8%.

Can I file a paper AT1? Not for most corporations. For taxation years beginning after December 31, 2024, the AT1 must be net filed unless the corporation is an insurance corporation, non-resident, reports in a functional currency or is exempt under section 35. The penalty for not net filing is $1,000.

Does my small corporation have to pay Alberta tax instalments? Not if it's a CCPC claiming the Alberta small business deduction with taxable income of $500,000 or less in the current or previous year, or if its Alberta tax is $2,000 or less. It then pays by the end of the third month after year end.

What's changing with TRACS on November 14, 2026? The PIN enrolment process ends. Account owners must be listed directors with a verified Alberta.ca account or an Interac document check, and that's validated at each login.

This guide is general information based on the Government of Alberta's corporate income tax and rates pages and CRA guidance as of October 2026. It isn't tax advice for your situation.

For help lining up the T2 and AT1 schedules, or the TRACS changes before November 14, RKube Services can be reached at (984) 234-7030.