T4 slips and the T4 return

What this does

The T4 return holds one slip for each employee paid in the year, plus the T4 Summary. SeroPayroll builds the XML file you upload to CRA and the PDF copies you give to employees.

Steps

1. Finish the checklist. See Year-end readiness.
2. Go to Year-End and pick the year.
3. Under Slips and returns, choose T4 return (XML).
4. The app checks the file against CRA's 2026 schema before it saves it. If the check passes, the file is saved.
5. Upload the XML to CRA with CRA's Internet File Transfer service. SeroPayroll does not upload it for you.
6. Choose T4 employee copies to make a PDF of the slips for employees.

If the check fails

The file is not saved and not recorded. The message says "The T4 return does not pass CRA's checks" and lists each problem by element, followed by "…and {count} more" if there are many. Fix the data and try again.

Filing history

Under {year} filing history, each saved return shows "T4 {year} · {reference}" and "{count} slips · {status}". Choose Save the XML again to download the file again. If nothing is saved yet, it says "No T4 return prepared for this year yet."

Good to know

• Employee copies show the SIN with only the last three digits.
• The T4 Summary is part of the XML return. The 2026 schema has no remittance or difference elements on the summary.
• The T4 shows the dental benefits code (box 45) from the employee, or the company default.
• The app builds original returns from the screen. Amended and cancelled returns are not on a screen.
• The XML return is not available under a trial licence, and the PDF carries the trial mark.
• A slip is split by province when an employee moved between provinces.
• The checker does not test identity constraints and xsi:type.