Somewhere in Canada right now, a payroll administrator is staring at a T4 slip wondering if Box 16 should match Box 14. It should not. And the fact that this trips up experienced payroll people every single year tells you everything about how unnecessarily confusing the CRA has made this process.

A T4 slip in Canada is the official Statement of Remuneration Paid that every employer must issue to employees and file with the CRA by the last day of February each year. It reports employment income, tax deducted, CPP and EI contributions, and taxable benefits for the previous calendar year. For the 2025 tax year, your T4 filing deadline is February 28, 2026.

We process thousands of T4s through Workzoom every year-end. And the same mistakes come back like clockwork. This guide covers what is on a T4, when it is due, how to fix errors, and the penalties that hit when things go sideways.

What Is a T4 Slip and Who Needs One?

The T4, officially called the “Statement of Remuneration Paid,” is the CRA’s record of what you paid each employee during the calendar year. Every employer who paid employment income, taxable allowances or benefits, or any other amounts requiring a T4 information return must file one for each employee.

That includes part-time staff. Seasonal workers. The summer student who worked six weeks. If you withheld CPP, EI, or income tax, they get a T4.

There is a related slip, the T4A, which covers different types of income: pensions, retiring allowances, self-employed commissions, and other payments that are not regular employment income. Do not mix them up. The CRA treats a T4A filed as a T4 as an error that needs correcting.

One thing that catches smaller employers off guard: even if an employee earned so little that no deductions were required, you may still need to issue a T4 if you reported the income as pensionable or insurable. When in doubt, file it. The CRA does not penalise you for issuing a T4 that was not strictly necessary. They absolutely will for not issuing one that was.

The T4 Deadline: February 28, and the CRA Means It

For the 2025 tax year, the filing deadline is February 28, 2026. That is the date by which you must:

• File all T4 slips and the T4 Summary with the CRA
• Distribute individual T4 slips to every employee

There is no extension. The CRA does not care that your payroll system was being migrated, or that your payroll person was on leave, or that you just discovered a taxable benefit you forgot to track all year. February 28 is February 28.

If February 28 falls on a weekend or statutory holiday, the deadline shifts to the next business day. For 2026, February 28 is a Saturday, which means your actual deadline is Monday, March 2, 2026. But do not plan around the grace day. Plan around getting it done early enough that you can catch errors before they are submitted.

The employers who panic in February are almost always the ones who left taxable benefits tracking to year-end. Track them on every pay run. February becomes boring. That is the goal.

What Is on a T4 Slip: The Boxes That Matter

A T4 has over 30 boxes. Not all of them will apply to every employee. But the ones that apply need to be right, because the CRA cross-references them against your remittance records and your employees’ personal tax returns.

Here are the boxes that cause the most confusion.

Box 14: Employment Income

This is the big number. Total employment income before deductions. It includes salary, wages, bonuses, commissions, taxable allowances, and the taxable value of benefits. Everything the employee earned or received that counts as employment income.

The mistake people make: leaving taxable benefits out of Box 14 but including them in Box 40. Box 14 needs the full picture. If an employer-paid group life insurance premium creates a taxable benefit, it goes in Box 14 and gets detailed in the relevant benefit box.

Box 16: Employee’s CPP Contributions

This is the total CPP (or QPP for Quebec) the employee contributed through payroll deductions for the year. Not what the employer matched. Just the employee side.

Box 16 will not match Box 14. It should not. CPP is calculated only on pensionable earnings between the basic exemption ($3,500) and the first ceiling ($74,600 for 2025). If Box 16 equals the maximum employee contribution for the year, that just means the employee earned above the ceiling. Normal.

Box 16A: Employee’s CPP2 Contributions

New since 2024. This reports the employee’s second additional CPP contributions on earnings between the first and second ceilings. If your employee earned between $68,500 and $79,400 in 2025 (the first year’s ceilings), this box will have a value. If they earned below the first ceiling, it will be blank.

CPP2 is still tripping up payroll software that has not been updated. If your Box 16A does not look right, check whether your system is treating CPP2 as a separate ceiling calculation or incorrectly rolling it into the base CPP rate.

Box 18: Employee’s EI Premiums

Total EI premiums deducted from the employee during the year. Remember that Quebec employees pay a reduced EI rate because QPIP covers parental benefits separately. If you have employees in multiple provinces, spot-check the Quebec slips to make sure they reflect the lower rate.

Box 22: Income Tax Deducted

Total federal and provincial tax withheld during the year. This box matters enormously to your employees because it determines whether they owe money or get a refund when they file their personal return.

If this number is wrong, your employee finds out in April when the CRA sends them a notice of reassessment. That conversation is never pleasant.

Box 10: Province of Employment

Two-letter code for the province or territory where the employee reports to work. This determines which provincial tax rates were applied.

With remote work, this box has become a minefield. If an employee worked from Ontario for January through June and then moved to B.C. in July, the CRA expects the T4 to reflect where they were actually working. For employees who worked across multiple provinces, you may need to issue separate T4 slips for each province. Check CRA’s guidance on multi-jurisdiction employees if this applies to your workforce.

Electronic Filing: It Is Not Optional Anymore

If you are filing more than 5 T4 slips, you must file electronically. The CRA eliminated the paper option for virtually every employer years ago. The threshold used to be 50 slips. Then they dropped it. Now it is 5.

You have three options for electronic filing:

• CRA Web Forms: Manual data entry through the CRA website. Free but painful for anything more than a handful of slips. You are typing every box for every employee.
• Internet file transfer (XML): Your payroll software generates an XML file and you upload it through CRA’s secure portal. This is how most mid-size employers do it.
• Payroll software with direct CRA integration: The software files directly. You review, approve, and it transmits. Fastest and least error-prone.

The XML route is where errors concentrate. If your software exports the file but you have not reconciled your payroll data first, you are just submitting errors faster.

Penalties for Late or Incorrect T4 Filing

The CRA’s penalty structure for late T4 filing is straightforward and merciless.

For filing after the deadline:

• $100 for each day the T4 Summary is late, up to a maximum of $7,500
• The penalty is calculated per information return (the summary), not per slip
• Minimum penalty of $100 even if you are one day late

For failing to file electronically when required:

• $250 penalty for filing more than 5 slips on paper

For incorrect information on T4 slips:

• If the error results in a shortfall of remittances, the CRA will assess the difference plus interest dating back to when the correct amount should have been remitted
• Repeated errors in consecutive years can trigger a $2,500 penalty per instance under the third-party civil penalties provision

And here is the part nobody mentions. If the CRA finds that you under-remitted because of T4 errors (say, you forgot to include a taxable benefit in pensionable earnings), the penalty is not just on the T4 itself. They reassess the CPP and EI contributions you should have remitted throughout the year. With interest. Going back to the first pay period where the error occurred.

A $500 taxable benefit you forgot to track can easily balloon into a four-figure reassessment once you add the employer CPP match, employer EI premium, and twelve months of compound interest.

How to Amend a T4 Slip

You filed. You found an error. Now what.

The good news: you can amend T4 slips after filing. The CRA accepts amended slips at any time. The bad news: amending does not erase the penalty for the original error if it resulted in a remittance shortfall.

Amending Online

If you filed electronically, you can submit amended T4s through the same channel. The CRA’s system will match the amended slip to the original using the employee’s SIN and the tax year.

Amending by Paper

If you need to amend a slip filed through Web Forms or XML, you can submit a paper amendment by marking the T4 as “Amended” and mailing it to your tax centre. But realistically, electronic amendment is faster and creates a clearer audit trail.

What Actually Triggers an Amendment

The most common reasons we see employers amend T4s:

• Discovered a taxable benefit that was not tracked during the year (parking, group insurance, company vehicle)
• Employee’s province of employment was coded incorrectly
• Retroactive pay adjustment after the T4 was filed (bonus paid in January for prior-year work)
• CPP or EI over-deduction that was not caught before filing

If the amendment is in the employee’s favour (you over-withheld), they will get it back when they file their personal return. If the amendment means they owe more, you need to issue the corrected T4 so their return is accurate. Either way, amend promptly. Do not wait and hope nobody notices.

The Five T4 Mistakes We See Every Year

After 25 years of Canadian payroll, these are the errors that never seem to die. Every February. Like clockwork.

1. Taxable benefits vanish into thin air

Employer-paid group life insurance over $25,000. Personal use of a company vehicle. Employer-paid parking. Gift cards above $500. These all create taxable benefits that need to appear on the T4. And every year, employers forget to track at least one of them.

The fix is not a year-end audit. The fix is including taxable benefits on every pay run so they are already calculated by the time T4 season arrives. If you are scrambling to calculate the standby charge on a company vehicle in February, you are already behind.

2. CPP pensionable earnings do not match

Box 26 (CPP pensionable earnings) and Box 14 (employment income) are related but not identical. Certain income types are included in Box 14 but exempt from CPP. When these boxes do not reconcile logically, the CRA’s automated matching flags the return for review.

3. Province of employment defaults to head office

Your company is in Ontario. Your remote developer is in Nova Scotia. If Box 10 says “ON” for that developer, you withheld the wrong provincial tax all year. The T4 is wrong, the employee’s return will be wrong, and eventually the CRA will sort it out with a reassessment that nobody enjoys.

4. Forgetting to issue T4s for terminated employees

Someone left in March. You paid them severance. You issued their final paycheque. Then year-end rolls around and they are not in the “active” employee list anymore, so the system skips them. Or worse, you assume someone else handled it.

Every person you paid employment income to during the year needs a T4. Current, terminated, retired, on leave. Everyone.

5. Filing the T4 Summary with wrong totals

The T4 Summary (T4-SUM) is the roll-up of all individual T4 slips. The totals on the Summary must match the sum of all individual slips, and they must reconcile with your total remittances for the year. A mismatch between your Summary and your remittance account is the fastest way to trigger a CRA balance-due notice.

Quebec Employers: RL-1 Slips Are a Separate Obligation

If you have employees in Quebec, you are not just filing T4s. You also file RL-1 slips with Revenu Quebec. Same deadline. Different form, different boxes, different rules.

The RL-1 reports Quebec-specific deductions: QPP instead of CPP, QPIP (Quebec Parental Insurance Plan), and Quebec provincial tax. The boxes do not map 1:1 to the T4, which means you cannot just copy T4 data into an RL-1 template. The calculations are different in ways that matter.

If your payroll system handles Quebec natively, the RL-1 generates alongside the T4 from the same payroll data. If it does not, you are looking at a manual reconciliation process that is tedious, error-prone, and due the same day everything else is due.

Making Year-End Boring on Purpose

The best payroll teams we work with do not dread February. They barely notice it.

Not because they are smarter. Because their systems do the work throughout the year instead of dumping it into a six-week sprint. Taxable benefits calculated on every pay run. Province of employment updated when it changes. CPP2 handled as a native calculation, not a manual override.

By the time February arrives, generating T4s is just pressing a button. Reviewing the output. Submitting to the CRA. Done.

That is what year-end should feel like. Not a panic. Not a project. A formality.

If your current process involves exporting to spreadsheets and praying your T4 Summary matches your remittances, the system is the problem. And the system is fixable.