Tax season checklist for accounting firms
Updated October 12, 2026
The short answer
Request documents and send engagement letters in January, file T4s and T5s by the last day of February, work back from April 30 for personal returns, treat June 15 as the filing date for self-employed clients, and plan capacity so the final weeks aren't a pile-up.
| January | Send slip and document requests; confirm engagement letters; start T4 and T5 preparation |
|---|---|
| February (last day) | T4, T4A and T5 slips and summaries due |
| March 1 | RRSP contribution deadline for the previous tax year (in a non-leap year) |
| April 30 | Personal (T1) returns and any balance owing due |
| June 15 | T1 filing date for self-employed clients; balance still due April 30 |
Start with what is outstanding
The most common cause of a late season is waiting on clients. Send each client a checklist of what you need, track what has arrived, and send reminders only to those still outstanding. A portal that shows each client exactly what is missing replaces most of the follow-up email.
Plan capacity before the rush
Count the returns by type and by who prepares them, then compare to the hours available each week. If April's weeks are overbooked in January, you can still move work earlier, add help, or decline new work. In April, you can't.
Keep the other deadlines moving
Tax season doesn't pause GST/HST returns, payroll remittances or corporate filings. Keep one firm-wide list of everything due, sorted by date, so personal returns don't crowd out business filings. This guide summarizes federal rules published by the Canada Revenue Agency. Your situation may differ (a fiscal year that doesn't end December 31, a non-resident, a province with its own return), so confirm at canada.ca or with your accountant before relying on a date.
Frequently asked questions
When should a firm start tax-season prep?+
Most firms send document requests in January and plan capacity before then, since personal returns are due April 30.
What is due on June 15?+
Self-employed individuals, and their spouses or common-law partners, can file their T1 by June 15. Any balance owing is still due April 30.
Let Clerra track these for every client.
Add a client once and their full CRA and provincial calendar is built automatically. Weekends and holidays are handled.
Start free for 14 days