T4 Summary 2025: Employer Filing Guide & Deadline

Every Canadian employer that paid salary, wages, commissions, or taxable benefits in 2025 has to report it to the CRA on T4 slips — one per employee — and tie those slips together with a T4 Summary. Miss the deadline or file on paper when you should have filed electronically, and the penalties add up fast. Here is how the 2025 filing works.

What the T4 Summary Is

The T4 Summary (form T4SUM, “Summary of Remuneration Paid”) is the reconciliation form that totals every T4 slip you issued for the calendar year. It rolls up, across all employees:

• Total employment income (Box 14)
• Total CPP/QPP contributions
• Total EI premiums
• Total income tax deducted
• Total taxable benefits and other amounts

It is distinct from an individual T4 slip: a slip reports one employee’s earnings and deductions, while the Summary reports the company-wide totals so the CRA can match what you reported against what you remitted through the year. Think of the slips as the line items and the Summary as the control total.

The 2025 Filing Deadline — March 2, 2026

The base rule is that T4 slips and the T4 Summary are due the last day of February following the calendar year. For the 2025 tax year that would normally be February 28, 2026 — but February 28, 2026 falls on a Saturday.

When the due date lands on a Saturday, Sunday, or public holiday recognized by the CRA, the return is due the next business day. That pushes the 2025 T4 filing deadline to:

Monday, March 2, 2026

You also have to give each employee their copy of the T4 slip by the same date. Note that 2026 is not a leap year, so February has 28 days — the Saturday rollover, not a February 29, is what moves the date.

Electronic Filing Is Mandatory for More Than 5 Slips

The CRA requires electronic filing once you cross a low threshold:

• 5 information returns or fewer for the year — you may file on paper or electronically.
• More than 5 returns (6 or more) — you must file electronically, or face a penalty.

Most employers file through the CRA’s Web Forms service (handles up to 100 slips), Internet File Transfer (XML), or their payroll software. Web Forms creates the T4 Summary totals automatically as you enter slips.

If you file electronically, do not send a paper T4 Summary. The CRA’s guidance is explicit: electronic filers must not mail a paper copy of the T4 slips or the T4 Summary. The paper Summary still exists for the small minority of employers filing 5 or fewer slips by mail.

Penalties for Late or Incorrect Filing

Two separate penalties can apply:

1. Late filing — calculated per day late, based on the number of slips, from a minimum to a maximum that scales with how many slips you filed late.
2. Failure to file electronically — assessed per type of information return when you file more than 5 on paper. The CRA’s published example puts this at flat penalties per return type (for instance, $125 for a small overage band), so filing T4s on paper when you have more than 5 is its own avoidable charge on top of any late penalty.

Errors in the slips themselves — wrong SIN, missing boxes, mismatched CPP/EI — can trigger reassessment and follow-up, so the Summary totals should reconcile to your remittances before you file.

Reconciling Before You File — The PIER Check

The CRA runs a Pensionable and Insurable Earnings Review (PIER) after slips are filed, comparing the CPP and EI you deducted against what the employee’s earnings should have produced. Shortfalls become a balance you owe (often with the employer share too). Reconciling your T4 totals against your year’s remittances — and against what a payroll deductions calculator produces for each pay period — before you file is the cheapest way to avoid a PIER assessment.

Quebec Employers File Twice

Employers with Quebec employees file the federal T4 with the CRA and the RL-1 slip with Revenu Québec, because Quebec administers its own income tax, QPP, and QPIP. The federal T4 Summary does not replace the RL-1 Summary; both are due on roughly the same end-of-February timeline.

Step-by-Step Checklist

1. Reconcile your payroll records — total employment income, CPP/QPP, EI/QPIP, and tax withheld for the year.
2. Match those totals to your remittances; resolve any gaps before filing.
3. Prepare T4 slips for every employee (Boxes 14, 16/17, 18, 22, plus benefit boxes).
4. File electronically if you have more than 5 slips — Web Forms builds the Summary totals for you.
5. Distribute employee copies by March 2, 2026.
6. Keep your records for at least six years in case of a PIER review.

Key Takeaways

• The 2025 T4 slips and T4 Summary are due March 2, 2026 — the last-day-of-February rule rolled forward because February 28, 2026 is a Saturday.
• The T4 Summary (T4SUM) totals all your T4 slips; it is the company-wide control figure, not an individual slip.
• More than 5 slips must be filed electronically, and electronic filers must not mail a paper Summary.
• Reconcile CPP/EI before filing to avoid a PIER shortfall assessment.
• Quebec employers also file an RL-1 with Revenu Québec.

Sources

• CRA — Employers’ Guide: Filing the T4 Slip and Summary (RC4120)
• CRA — T4SUM Summary of Remuneration Paid
• CRA — T4 information for employers