CO-17 and T2: Quebec Corporate Tax Return Deadlines

Two returns, two tax authorities

A corporation that has an establishment in Quebec files two income tax returns every year:

Quebec is the only province that collects its own corporate income tax on a separate return. Revenu Québec states that a corporation with an establishment in Quebec at any time in a taxation year must pay tax on its taxable income for that year, calculated on the CO-17 ^[1]. It does not matter whether the company was incorporated federally (CBCA) or provincially: a federal corporation operating from Montreal files both returns.

This guide covers the mechanics: when to file, when to pay, how to file and what lateness costs. It is general information, not tax advice; whoever prepares the returns, the corporation signs them and pays the penalties.

If you have not yet opened your Revenu Québec accounts, start with our guide to Revenu Québec registration for GST/QST and source deductions.

Filing deadline: six months after year-end

Both returns are due six months after the end of the tax year.

• CRA: file within six months of the end of each tax year; the tax year of a corporation is generally its fiscal period. If the year ends on the last day of a month, the deadline is the last day of the sixth month after; if not, it is the same day of the sixth month ^[2].
• Revenu Québec: a corporation that must file the CO-17 must send it within the six months following the end of its taxation year ^[1].

The CRA's own examples:

Source: CRA, T4012. A December 31 year-end therefore files by June 30.

Weekend rule. If the deadline falls on a Saturday, Sunday or public holiday, the CRA treats the T2 as on time if it receives it or it is postmarked by the next business day ^[2]. Revenu Québec extends a filing deadline that expires on a Saturday, Sunday or holiday to the next business day ^[1].

Payment deadline is earlier: two or three months

This is the rule new owners miss. Filing is due at six months, but the tax is due much earlier, and interest runs from the payment date, not the filing date.

Federal (CRA). Generally, all corporation taxes are due two months after the end of the tax year. The balance of Part I tax is due three months after year-end if the corporation is a CCPC throughout the year, claims the small business deduction for the year (or was allowed it the previous year), and its taxable income for the previous year (or that of its associated group) did not exceed its business limit ^[2]. Most small owner-managed CCPCs meet these conditions; a company whose prior-year taxable income (with associated corporations) exceeded the $500,000 business limit drops back to two months for that year.

Quebec (Revenu Québec). A corporation with a balance owing after instalments must pay it within two months after the end of its taxation year to avoid interest ^[1]. The CO-17 guide states the same two-month rule and adds that interest is compounded daily at the prescribed rate on any balance unpaid after that date ^[3]. There is no Quebec equivalent of the federal three-month rule: every corporation, CCPC or not, pays its Quebec balance within two months ^[3].

Registraire fee. The annual registration fee for the enterprise register is paid to Revenu Québec with the CO-17, and is due no later than the last day of the second month after the end of the fiscal year. It is not payable for the year in which the company is first registered or for the following year ^[3].

Large payments. Since January 1, 2024, any payment to Revenu Québec over $10,000 must be made electronically unless special circumstances prevent it; otherwise a penalty may apply ^[1].

If the company owed more than $3,000 in tax in both the current and previous year, it should also have been paying instalments during the year ^[1]. Our 2026 Quebec tax instalment calendar covers the schedules.

Mandatory electronic filing

Paper is essentially gone for small corporations on both sides.

CO-17. For taxation years beginning on or after January 1, 2024, all corporations must file their return online, regardless of gross revenue, and a penalty may be imposed for non-compliance. Some corporations, such as tax-exempt non-profits, may be exempt ^[1]. Revenu Québec's May 2025 reminder repeats that every corporation must file online regardless of gross revenue (except charities), and that preparers who file more than five corporate returns for the same tax year must also file them online ^[4].

Online filing options: use certified commercial software yourself, have a preparer file with a power of attorney, or use an authorized preparer with form CO-1000.TE ^[1].

T2. For tax years starting after 2023, all corporations must file the T2 electronically, except insurance corporations, non-resident corporations, corporations reporting in a functional currency and corporations exempt under section 149 of the Income Tax Act. The CRA charges a $1,000 penalty for non-compliance (as of October 2026) ^[5].

What goes into the CO-17 and the T2

Financial statements. Revenu Québec requires complete financial statements with every CO-17: balance sheet, income statement, statement of retained earnings, cash flow statement and notes, plus documents supporting any tax credit claimed ^[1]. Federally, the financial statements are reported through the General Index of Financial Information (GIFI) schedules in the T2 software ^[5].

Schedules. Both returns carry schedules for capital cost allowance, dividends, shareholder information, the small business deduction, related corporations and so on. The CO-17 has its own set; Revenu Québec does not supply every schedule, and some must be created by copying the required information ^[1].

The guide. The Guide de la déclaration de revenus des sociétés (CO-17.G) is the line-by-line reference for the CO-17; the CRA's T4012 is the federal equivalent.

Software. Most accountants use one package that produces both returns from the same data. If you prepare the returns yourself, the software must be certified by both the CRA and Revenu Québec.

Typical document pack to hand to your accountant:

• trial balance or bookkeeping file at year-end;
• bank and credit card statements for the last month of the year;
• loan and lease agreements;
• list of fixed assets bought or sold;
• shareholder loan and dividend records;
• payroll summaries (T4/RL-1) and GST/QST returns;
• instalment payment confirmations from both authorities;
• notices of assessment from the prior year.

Penalties and interest

Sources: CRA, Avoiding penalties; CRA, Completing your T2 return; Revenu Québec, Late-Filing Penalties; CO-17.G, section 3.5.4.

Two practical points:

• The late-filing penalty is a percentage of unpaid tax. If you paid everything on time, a late return costs little in penalty, but you still lose time, may trigger a demand to file and expose yourself to the higher repeat-offender rate federally.
• Instalment interest is separate. Both authorities charge interest on late or insufficient instalments. The CRA adds an instalment penalty when instalment interest exceeds $1,000 ^[6], and Revenu Québec adds interest at 10% per year on any missed instalment unless at least 90% of the amount due was paid (CO-17.G).

Worked example (illustrative)

A Montreal software consultancy is a CCPC with a December 31, 2026 year-end and claims the small business deduction. It paid no instalments in its first year.

Suppose the company files both returns in mid-September 2027, about two and a half months late, with a $4,000 Quebec balance still unpaid. Under the Revenu Québec rule the late-filing penalty would be 5% of $4,000 ($200) plus 1% for each of the two full months ($80), so $280, plus daily compound interest on $4,000 since the end of February. Had the balance been paid in February, the late-filing penalty would have been nil. The same structure applies federally.

Your first fiscal year

A new corporation chooses its first year-end. The rules to know:

• A corporation's taxation year corresponds to its fiscal period and cannot exceed 53 weeks ^[3]. If you incorporate on March 15, 2026, your first year must end by mid-March 2027 at the latest.
• A short first year is allowed and common. A company incorporated in September can close its first year on December 31, producing a three-month return. That means a full set of returns and financial statements for a few months of activity, which some owners avoid by choosing a later year-end.
• December 31 aligns the corporate year with the owners' personal tax year and the T4/RL-1 calendar, but puts the corporate deadline in the same season as personal tax returns. An off-peak year-end such as March 31, June 30 or September 30 avoids that peak.
• Treat the first choice as long-term: once set, the fiscal period can be changed only with the CRA's concurrence ^[7].
• Write the first year-end, the two- or three-month payment dates and the six-month filing date into your calendar on the day you incorporate. Revenu Québec lets you subscribe to email reminders of the CO-17 due date in Mon dossier pour les entreprises ^[1].

Nil and inactive years

All corporations, including inactive ones, must file a T2 for every tax year, even when no tax is payable ^[2]. On the Quebec side, even if the corporation carried on no commercial operations during the year, it must attach a balance sheet showing its financial position at year-end (^[1]; CO-17.G).

A company you are not using still costs two returns, the Registraire's annual fee and the accounting fee each year. If you do not plan to restart, compare that with the cost of winding up; see our guide on how to close a business in Quebec.

Joint filing with the REQ annual update

Every corporation in the enterprise register must confirm or update its register information each year within the time allowed to file the CO-17, and pay the annual registration fee ^[1]. Line 39 of the CO-17 is where you do it: tick "Oui" if the register information is accurate, or "Non" and make the changes through Mon bureau at the Registraire des entreprises ^[3]. The information covered includes directors' names and home addresses and terms of office, officers, unanimous shareholder agreements, ultimate beneficiaries and bankruptcy status (same source).

Ticking "Oui" when a director left during the year is a common error. Check the register before your accountant files. For fees, deadlines and penalties on the annual update, see our French-language guide to the déclaration annuelle au REQ. For a business corporation, the annual updating declaration filed on time costs $106 (including the annual registration fee) as of October 2026 ^[8].

Calendar and checklist

One-page timeline (for a year-end on the last day of month M)

Checklist

• Year-end chosen and recorded; first year no longer than 53 weeks.
• Revenu Québec corporate income tax file and CRA business number active.
• Bookkeeping closed and reconciled within 30 to 45 days of year-end.
• Balance calculated before the two-month payment date.
• Quebec balance and federal balance paid electronically on time.
• Register information checked before ticking line 39.
• Both returns filed electronically by the sixth month.
• Assessments filed with the corporate records.

Government mail still matters even with online accounts. If your directors' home addresses are not where you want the company's mail to go, a business address in Montreal with mail scanning, such as 2727 Coworking's virtual mailbox plans, keeps CRA and Revenu Québec letters in one place.

Sources

1. Impôt des sociétés (Revenu Québec, French only)
2. Guide de la déclaration de revenus des sociétés, CO-17.G (Revenu Québec)
3. Late-Filing Penalties (Revenu Québec)
4. Rappel : transmission de documents et paiement par voie électronique, 27 May 2025 (Revenu Québec)
5. T4012 T2 Corporation Income Tax Guide: Before you start (CRA)
6. Completing your corporation income tax (T2) return (CRA)
7. Corporations: avoiding penalties (CRA)
8. Tarifs du Registraire des entreprises pour une société par actions (Québec.ca)
9. Income Tax Act, s. 249.1 (Justice Laws Website)