T1 Personal Tax Filing in Canada: A Firm's Guide to the Season
the April 30 and June 15 clocks and how firms run T1 season as a pipeline
The T1 General is the return most Canadian individuals file each year, due April 30 with any balance owing. Self-employed individuals and their spouses or common-law partners have until June 15 to file, but payment is still due April 30. Firms run T1 season as a pipeline — intake, slip collection, preparation, review, and electronic filing through CRA-certified software — because volume, not complexity, is what breaks practices.
Who files a T1, and when is it due?
Almost every Canadian resident with tax payable files a T1 General each year. Most individuals file and pay by April 30. Individuals with self-employment income — and their spouses or common-law partners — file by June 15, though any balance owing is still due April 30.
Filing can pay even where no tax is owing: benefit and credit entitlements are computed from the return, so a client with no balance due may still leave money unclaimed by not filing. Where a due date falls on a weekend or public holiday, the CRA treats the next business day as on time.
| Filing | Applies to | Filing deadline | Payment | If it is late |
|---|---|---|---|---|
| T1 personal income tax return | Most individuals. | File and pay by April 30 of the following year. Where April 30 falls on a weekend or public holiday, the CRA treats the next business day as on time. | Any balance owing is due April 30. | Late filing costs 5% of the balance owing plus 1% for each full month late, to a maximum of 12 months. Where a late-filing penalty applied in any of the three prior years and the CRA issued a demand to file, the penalty rises to 10% plus 2% per month for up to 20 months. Compound daily interest runs on unpaid balances from May 1. |
| T1 for self-employed individuals | Individuals with self-employment income and their spouses or common-law partners. | File by June 15. The extended filing date applies to the return only. | Any balance owing is still due April 30. Interest accrues from May 1 regardless of the June filing window — this is the single most-missed rule in Canadian personal tax. | The same 5% plus 1% per month structure applies, computed from the June 15 filing date; interest runs from the April 30 payment date. |
Why June 15 filers still owe interest from May
Because the extended date applies to the return, not the money. A self-employed client's balance is due April 30 whatever the filing date, and compound daily interest runs on unpaid amounts from May 1. The June window buys preparation time, not payment time.
The practical consequence for firms: every self-employed file needs a balance estimate in April, even where the return itself will be finished in June. Preparing the estimate and the return on separate tracks is what keeps the extended deadline from quietly costing the client interest.
What does a complete T1 file need?
Every information slip issued to the client, the prior-year notice of assessment, a record of instalments paid, and support for each deduction and credit claimed. Missing pieces surface late — usually as a CRA matching adjustment months after filing — so completeness at intake is the cheapest quality control.
The CRA receives copies of most slips directly from issuers and matches them against filed returns, which means an omitted slip is found eventually whether or not the client remembers it. A firm checklist per client, carried forward from last year's file, catches most gaps before preparation starts.
- Employment and pension slips: T4, T4A and related slips issued for the year
- Investment and trust slips: T5, T3 and any partnership allocations
- Prior-year notice of assessment, including RRSP room and carry-forward amounts
- Instalments paid during the year, reconciled to the CRA's record
- Receipts and support for deductions and credits claimed: RRSP contributions, medical, donations, childcare
- Self-employment records where a T2125 is part of the return
How do firms file T1 returns with the CRA?
Through EFILE: registered preparers transmit clients' returns electronically using CRA-certified tax software. NETFILE is the parallel service for individuals filing their own returns. EFILE registration is per firm and renewed with the CRA — it is a credential, not just a software feature.
Authorization is the other half of the machinery. A client's consent, requested through the preparer's software or CRA portals, gives the firm representative access to the client's CRA account — slips on file, carry-forward amounts, instalment balances — which is what makes pre-filing verification possible rather than aspirational.
Why Québec clients file two returns
Québec administers its own personal income tax, so residents of Quebec file a provincial TP-1 return with Revenu Québec alongside the federal T1. Two returns, two assessments, two sets of correspondence — a firm serving Québec clients runs both tracks on every file.
How firms run hundreds of T1s as a pipeline
By treating the season as stages with owners, not a pile with a deadline. Intake, slips complete, prepared, reviewed, client-approved, filed — each return sits in exactly one stage, and the firm reads its season from the counts per stage rather than from memory.
The dates themselves are the easy part; January reminders, an April payment checkpoint for self-employed files, and a named owner per return are what firms in this position typically formalise. What breaks a T1 season is rarely a rule nobody knew — it is a file nobody was watching.
Frequently asked questions
What is a T1 General?
The T1 General is the income tax and benefit return Canadian individuals file each year with the Canada Revenue Agency. It reports income from all sources, claims deductions and credits, and computes the refund or balance owing. Benefit and credit entitlements are calculated from it, which is why filing matters even in years where no tax is payable.
Do self-employed clients really have until June 15?
To file, yes — to pay, no. Individuals with self-employment income, and their spouses or common-law partners, have until June 15 to file the T1, but any balance owing is due April 30 and compound daily interest runs from May 1 on unpaid amounts. Firms estimate the balance in April even when the return will be completed in June.
What documents should a firm collect for a T1?
Every slip issued to the client — T4, T4A, T5, T3 and any others — plus the prior-year notice of assessment, a record of instalments paid, and support for each deduction and credit claimed. The CRA matches filed returns against slips it already holds, so an omitted slip is eventually found; a carried-forward checklist per client catches gaps before preparation starts.
What happens if a T1 is filed late?
The CRA charges a late-filing penalty of 5% of the balance owing plus 1% for each full month late, to a maximum of 12 months, with compound daily interest on unpaid balances. Where a late-filing penalty applied in any of the three prior years and the CRA demanded a return, the penalty rises to 10% plus 2% per month for up to 20 months.
What is EFILE?
EFILE is the Canada Revenue Agency's electronic filing service for registered tax preparers, who transmit clients' returns using CRA-certified software. NETFILE is the equivalent service for individuals filing their own returns. EFILE registration belongs to the firm and is renewed with the CRA — a practice files under its own credential, not the client's.
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