I filed my taxes and then a T3 showed up

You do have to fix it, and it is much less painful than it sounds. This is one of the most common tax-season annoyances for Canadian dividend investors, and it is entirely a scheduling problem.

Why it happened

Different investments report on different timetables, and almost nobody is told this in advance.

T5 slips come from corporations — a bank paying you a dividend directly. The deadline is around the end of February, which lines up neatly with when most people start thinking about filing.

T3 slips come from trusts. Most Canadian-listed ETFs and income funds are structured as trusts, so if you hold Canadian income ETFs you are getting T3s. The deadline is later — typically around the end of March — because the fund cannot finalise its numbers until its own year-end accounting is complete.

That gap is the whole problem. If your filing habit was formed on employment income and T4s, early March feels late. For a portfolio of Canadian income ETFs it is early.

Why the fund cannot just tell you sooner

A T3 does not only report an amount. It reports the characterisation — how much of the year’s distributions was eligible dividends, capital gains, foreign income, other income, and return of capital.

The fund cannot know that split until it has closed its books, reconciled what its own underlying holdings paid it, and worked out what was realised. Several of those inputs arrive from third parties on their own schedules.

Which also explains the second annoyance:

Amended slips are normal

If you hold funds with complex distributions — covered call funds, funds holding other funds, anything with meaningful foreign content — an amended T3 is a routine event, not a sign that something went wrong. The initial characterisation is sometimes an estimate that gets revised once everything reconciles.

Getting an amended slip in May, after a March slip you already used, is ordinary.

What to do now

Do not file a second return. The mechanism is an adjustment.

• Online: “Change my return” in CRA My Account. Fastest route, and for a straightforward slip addition it is usually processed without any correspondence.
• Software: most Canadian tax packages can generate a T1-ADJ from a re-run of the return.
• Paper: form T1-ADJ, mailed. Slowest.

You generally have ten years to adjust a return, so there is no urgency in the sense of a deadline. There is urgency in a different sense: if the missing slip means you underpaid, interest accrues from the original balance-due date. Fixing it sooner costs less.

A few practical notes:

• The CRA already has the slip. Issuers file copies. Their matching program will find the discrepancy in due course, so this is not something to leave and hope about.
• A single missed slip is not a penalty situation in the ordinary case. Repeatedly failing to report income — the rule generally bites on a second occurrence within a four-year window — is where real penalties appear. One correction, made voluntarily, is routine housekeeping.
• Check “Auto-fill my return” before adjusting. If other slips arrived late too, catch them in the same correction rather than filing three separate adjustments.

How to stop it happening again

Do not file until April if you hold Canadian income ETFs. This is the entire fix and it costs you nothing. There is no advantage to filing in early March; a refund arrives a few weeks earlier, which is not worth an amended return.

Wait for CRA Auto-fill to settle. Slips populate progressively. Checking in mid-April shows you a far more complete picture than checking in early March.

Keep your own record of distributions. You should be doing this anyway for adjusted cost base — if you have logged every payment as it arrived, you will notice immediately when a slip is missing rather than discovering it in an envelope.

Know which of your holdings are trusts. If you hold only Canadian corporations directly, you will be dealing with T5s and can file earlier. The moment ETFs enter the portfolio, the timetable moves.

The one that actually costs money

While you are correcting the return, use the opportunity to check the return of capital figure on the slip.

That number is not just a tax-year detail — it permanently reduces the adjusted cost base of the holding, and the effect accumulates for as long as you own it. It is the figure people most often fail to record, and reconstructing years of it later is genuinely difficult.

If nothing else comes out of an amended return, let it be the habit of writing that number down every year. The cost base calculator shows what it does to the gain waiting when you eventually sell, and how dividends are taxed in Canada explains where it sits among the other boxes on the slip.