Keeping an audit-ready record of your deductible interest

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When you borrow to invest in Canada, claiming the interest deduction is only half the job. The other half is being able to show your work — a clear record of how much of your interest was deductible, and why, for every year you claim it. If the CRA ever reviews the claim, the burden is on you to demonstrate that the borrowed money can be traced to an income-earning purpose.

Why a single deductible number isn't enough

A lender's statement tells you the total interest you paid. It does not tell you how much of that interest was deductible — and for a leveraged-investing or Smith Manoeuvre setup, those are rarely the same number. The deductible portion depends on the current use of the borrowed money, which shifts every time you transact:

• Selling holdings can turn deductible debt non-deductible until you reinvest the proceeds.
• Return of capital reduces the amount traceable to your investments — sometimes retroactively.
• Personal use of the credit line blends deductible and non-deductible debt.
• Capitalized interest takes on the deductible character of the debt underneath it.

Because the deductible proportion moves throughout the year, the interest deduction has to be time-weighted across the periods your debt composition actually held — not estimated from a year-end snapshot.

What “audit-ready” really means

An audit-ready record doesn't just state a deductible total. It can reconstruct that total from first principles — walking event by event through the year and showing the effect of each one on your deductible and non-deductible balances. A defensible record can answer:

1. How much was borrowed, when, and what it was used for.
2. Which transactions changed the deductible proportion, and by how much.
3. How each interest charge was split into deductible and non-deductible amounts.
4. How that reconciles to the totals you reported on your return.

Over a single clean year, a spreadsheet can approximate this. Over several years of partial sales, distributions, and capitalized interest, the trace compounds — and a number you can't explain is a number you can't defend.

How the tracker produces one

The Deductible Interest Tracker keeps the deductible split correct from your actual events, then turns it into a report you can hand to your accountant or keep on file. Every interest charge is traced back to the events that shaped it, so each figure comes with an explanation of how it was reached — the same event-by-event logic described in how balances are tracked.

It pairs naturally with the two other records leveraged investors need: your adjusted cost base (including the borrowed portion) and, if you want the refund sooner, a T1213 request to reduce tax at source.