How to File T4 Slips for Ontario Employees Step by Step

Table of Contents

• What You’ll Need Before You Start Filing T4 Slips
  • Gather Employee Records and Payroll Data
  • Set Up Your CRA Business Account and Web Access Code
• Step 1: Reconcile Payroll and Verify CPP, EI and Tax Deductions
  • Check Gross Pay, Pensionable Earnings and Insurable Earnings
• Step 2: Report Taxable Benefits and Allowances on Each T4 Slip
• Step 3: How to Use CRA Web Forms for T4 Filing
  • Entering Data and Validating Before Submission
  • Manual Entry vs. Certified Payroll Software
  • Troubleshooting Common Submission Errors
• Step 4: Meet the CRA T4 Filing Deadline and Avoid Penalties
• Step 5: Correcting T4 Slips After Filing (Amendments and Cancellations)
• Ontario-Specific Considerations: EHT and Remote Employees
  • Integrating Employer Health Tax (EHT) with T4 Reporting
  • Filing T4s for Remote Employees Working in Ontario
• Common Mistakes to Avoid When Filing T4 Slips
• Frequently Asked Questions

Last Updated: September 16, 2026

What You’ll Need Before You Start Filing T4 Slips

Filing T4 slips for Ontario employees starts with one clean payroll file. This guide covers reconciling deductions, reporting taxable benefits, filing through CRA Web Forms, and fixing slips after submission.

Gather Employee Records and Payroll Data

You need each employee’s legal name, social insurance number, date of birth, and current address, plus every pay period’s gross pay, deductions, and employer contributions. Pull the full calendar year, a missing month often surfaces only when the totals refuse to balance.

• Employee legal name, SIN, and address for every person paid
• Gross pay by pay period for the full year
• CPP contributions, EI premiums, and income tax withheld
• Employer-side CPP and EI amounts
• Taxable benefits and allowances granted
• Prior remittances already sent to the CRA

Set Up Your CRA Business Account and Web Access Code

A business number is the nine-digit CRA identifier for your company, with a two-letter payroll program account attached. If you have never registered a payroll account, that comes first; then request a web access code through the CRA’s online services to file electronically.

Step 1: Reconcile Payroll and Verify CPP, EI and Tax Deductions

Payroll reconciliation decides whether your slips survive CRA review. Compare what you remitted against what your records say you owed, every gap becomes a corrected slip later, so find it now.

Check Gross Pay, Pensionable Earnings and Insurable Earnings

Pensionable earnings are the wages on which CPP contributions are calculated, excluding most non-cash benefits. Insurable earnings are subject to EI premiums and include most taxable benefits. Confusing the two is the most common cause of rejected slips.

• Gross pay: total wages before any deduction
• Pensionable earnings: gross pay minus CPP-exempt items
• Insurable earnings: gross pay plus most taxable benefits
• Statutory deductions: CPP contributions, EI premiums, and income tax

Step 2: Report Taxable Benefits and Allowances on Each T4 Slip

Taxable benefits and allowances belong on the slip even when no cash changed hands, a company vehicle used personally, a group life insurance premium, or a taxable allowance for a tool or travel all count. Report each in its correct box; the CRA cross-checks benefit boxes against your corporate return.

Step 3: How to Use CRA Web Forms for T4 Filing

CRA Web Forms is the free browser tool for filing up to 100 slips without accounting software. You enter each slip manually and the system validates the data before accepting your submission. It suits a small payroll with clean records, not a distributed team, a mid-year province change, or a payroll reconstructed from bank statements.

Entering Data and Validating Before Submission

Work one slip at a time and let the tool catch errors as you go. Web Forms flags a missing SIN, an out-of-range income figure, or a pensionable amount that doesn’t match the CPP maximum for the year, and won’t transmit a file that fails its internal checks, safer than a spreadsheet for a first-time filer.

A practical sequence that works for most small employers:

1. Enter the employer identification block once, business number, payroll program account, and year.
2. Enter each employee slip, starting with the highest-paid employee so the CPP and EI maximums get consumed correctly.
3. Run the built-in validation and clear every flag before adding the next slip.
4. Review the summary totals against your reconciliation from Step 1.
5. Transmit, then save the confirmation number immediately.

Manual Entry vs. Certified Payroll Software

The choice between Web Forms and certified software is about how many edge cases your payroll contains, not size alone.

Troubleshooting Common Submission Errors

Most rejected submissions fall into a small set of recurring causes. Knowing them turns a February panic into a five-minute fix.

• SIN mismatch or invalid SIN. The CRA cross-checks the SIN against its records. A transposed digit or a SIN that does not match the employee’s name on file will reject the slip. Verify SINs at hire and keep the confirmation.
• Pensionable or insurable earnings out of range. If pensionable earnings exceed the year’s CPP maximum, or insurable earnings exceed the EI maximum, the file will flag. This usually means a benefit was included in the wrong earnings category.
• Missing province of employment. Every slip needs a province code. A blank or invalid code rejects the slip.
• Duplicate slip for the same employee. Filing the same SIN twice in one year triggers a rejection. Check your employee list for duplicates before transmitting.
• Summary totals that don’t match the slips. The T4 Summary must reconcile to the sum of the slips. A single transposed figure will block the whole submission.
• Wrong tax year. Filing a 2025 slip under the 2026 tax year is a common copy-paste error when you are catching up on multiple years.

Step 4: Meet the CRA T4 Filing Deadline and Avoid Penalties

The CRA T4 filing deadline is the last day of February following the tax year, for both slips and summary. Miss it and the penalty is calculated per slip, per day, escalating fast on any size of payroll.

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Step 5: Correcting T4 Slips After Filing (Amendments and Cancellations)

Correcting T4 slips after filing means submitting an amended slip when a figure was wrong, or a cancelled slip when the slip should never have existed. Both go through the same electronic channel you filed with and require the original slip’s identifying details.

Ontario-Specific Considerations: EHT and Remote Employees

Two Ontario wrinkles catch employers who file a clean federal T4 and assume the job is done: the provincial payroll tax outside the T4 system, and the employee who moved during the year.

Integrating Employer Health Tax (EHT) with T4 Reporting

The Employer Health Tax is an Ontario payroll tax on remuneration paid to employees in the province, separate from federal source deductions. Your T4 figures feed the EHT calculation, so a reconciliation error propagates into your provincial return too.

The mechanics that matter for a T4 filer:

• Registration. EHT registration is separate from your CRA payroll account. An employer with Ontario remuneration above the exemption threshold must register with the province and file an annual return.
• Exemption threshold. Ontario applies an exemption amount to the first slice of payroll, and the threshold differs for private-sector employers versus charities and non-profits. Confirm the current figure with the province each year, because it is indexed.
• Return schedule. Most employers file annually, but larger payrolls file installments. The annual return is due in March following the calendar year, later than the T4 deadline, which is why employers often forget it exists.
• The T4 link. The total Ontario remuneration on your EHT return should tie back to the sum of Box 14 (employment income) on your Ontario slips, adjusted for items EHT treats differently. Get the T4 total right and the EHT return becomes a matter of copying a number rather than rebuilding it.

Ontario Employer Health Tax registration and rates

Filing T4s for Remote Employees Working in Ontario

An employee’s T4 province of employment is generally where they report to work, not where your office sits (Determine the province of employment (POE)). A remote worker based in Ontario belongs on an Ontario slip even if your business is registered elsewhere, and provincial tax withholding follows the same rule.

A few practical rules for distributed teams:

• Set province by work location, not by home office. The employee’s reporting location drives the slip.
• Document the change date. If an employee moved from another province to Ontario in, say, July, you need the exact date to split the year correctly.
• Watch the cross-border case. An employee who works remotely from outside Canada is a different situation entirely and may not belong on a T4 at all. Confirm the residency rules before filing.
• Reconcile provincial tax withheld separately. Ontario provincial tax is a distinct line from federal tax, and a mismatch between what you withheld and what the slip reports will flag on review.

Common Mistakes to Avoid When Filing T4 Slips

The costliest errors are rarely exotic, the same handful of omissions repeated across thousands of small payrolls every February.