Adjusted cost base (ACB) tracking is the record-keeping obligation that Canadian investors carry for every security in a taxable account. Canadian identical-property rules can require a weighted-average cost across non-registered accounts under the same ownership. A broker figure can help with the calculation, but CRA says T5008 Box 20 may or may not reflect ACB and must be adjusted as needed.
This page explains what a complete ACB tracker needs to do and how myCostBase handles each piece of the tracking problem for Canadian investors.
What an ACB tracker needs to maintain
An ACB tracker is not a one-time calculator. It is a running ledger that updates every time something happens to a position:
| Event | ACB effect |
|---|---|
| Purchase (Buy) | Increases total ACB and share count; recalculates ACB per share |
| Sale (Sell) | Reduces share count; ACB per share stays the same |
| DRIP reinvestment | Increases total ACB and share count at the reinvestment price |
| Return of capital (T3 Box 42) | Reduces total ACB without changing share count |
| Phantom income distribution | Increases total ACB without changing share count |
| Stock split | Changes share count; total ACB stays the same; ACB per share recalculates |
| Transfer in (from another broker) | Adds shares at original acquisition cost — not market value on transfer date |
| Transfer out | Removes shares; ACB per share stays the same |
| USD purchase | Records the CAD equivalent with its exchange-rate source and date |
Each event changes the denominator or numerator of the running weighted average. Missing even one event — a single return-of-capital adjustment or a DRIP from a prior year — causes every subsequent calculation to carry forward the error.
Why ACB tracking is not the same as watching your brokerage balance
Your brokerage may show book value for a position. That figure can be useful for tracking unrealized gains and reconciling your records, but it is not conclusive: you must verify whether it includes every event relevant to the Canadian ACB calculation.
Broker book value and the calculated ACB can diverge when:
- You hold the same security at more than one taxable brokerage
- You transferred shares between brokerages and the receiving account has incomplete or placeholder cost information
- You hold ETFs or trusts that pay return-of-capital distributions
- You trade USD securities (the broker’s FX rate may differ from the Bank of Canada rate)
- You participate in DRIP through a transfer agent rather than through the brokerage
For a detailed breakdown of these scenarios, see Broker Book Value vs Adjusted Cost Base in Canada.
Pooled ACB across multiple brokerages
The most common ACB tracking difficulty in Canada is multi-brokerage pooling. The Income Tax Act requires you to treat all identical securities held in taxable accounts under the same ownership as a single pool — regardless of which broker holds them. Each broker only reports book value for its own account, so neither one shows you the pooled figure CRA requires.
That’s a one-time reconciliation if you never trade again — but a tracking problem the moment a third purchase, a transfer, or a sale happens at either broker, since the pooled ACB has to be recalculated from the combined history every time. For the full worked example — two brokerages, the weighted-average math, and what happens if you use the wrong figure — see Pooled Adjusted Cost Base Across Multiple Brokerages.
ACB tracking for ETF investors
Canadian ETFs — particularly fixed-income ETFs, real estate funds, and some broadly-diversified equity ETFs — regularly pay distributions that include a return-of-capital component. These appear on your annual T3 slip in Box 42.
Return-of-capital distributions are not income — they are a return of part of your original investment. For ACB purposes, each ROC distribution reduces your adjusted cost base by the per-unit amount, even though you receive no new shares.
A tracker that doesn’t apply T3 Box 42 adjustments will overstate your ACB, which understates your capital gain at sale. After several years of ROC distributions, the gap can be significant.
For the mechanics and a worked example, see ETF Return of Capital and Adjusted Cost Base.
ACB tracking for USD investments
When you purchase a U.S.-listed stock or ETF in a Canadian taxable account, record the ACB in Canadian dollars using a documented rate applicable to the transaction. CRA generally points to the Bank of Canada daily exchange rate, while also accepting qualifying alternative sources and averages in certain circumstances. Retain both trade and settlement dates for exchange-traded shares.
On a CAD-denominated ACB, you apply the same pooled weighted average as for CAD securities. On a disposition, convert the proceeds using the supported, documented rate applicable to the transaction, then apply the CAD ACB to calculate the capital gain or loss.
IBKR users should reconcile the report’s rate source, date, and cost method to Canadian-dollar ACB rather than assuming either figure is automatically correct. For the evidence-based comparison, see Broker Book Value vs Adjusted Cost Base in Canada.
T5008 reconciliation as part of ACB tracking
Brokers and other securities dealers may issue T5008 slips or a consolidated statement for reportable dispositions. Box 20 is cost or book value, while Box 21 is proceeds of disposition or settlement amount.
A complete ACB tracking workflow includes reconciling Box 20 against your own ACB ledger before you file Schedule 3. CRA says Box 20 may or may not reflect ACB, so investigate any difference and use the amount supported by the applicable rules and your records. Keeping the reconciliation helps support the reported figure if CRA asks for more information.
The T5008 ACB reconciliation checker lets you compare Box 20 against your records and identify the likely reason for the discrepancy.
When to use a spreadsheet vs dedicated ACB tracking software
A spreadsheet is workable when:
- You have one taxable brokerage account
- You hold only individual Canadian stocks (no ETF distribution adjustments)
- You have no USD positions
- You have never transferred shares between brokers
- You have fewer than 20–30 transactions per year
A dedicated ACB tracker may be useful when any of the following applies:
- You hold the same security at two or more taxable accounts
- You hold ETFs with annual return-of-capital distributions
- You trade USD-listed securities
- You have transferred shares between brokerages
- You hold positions that span more than 5–7 years of transactions
The free ACB spreadsheet template is a good starting point for simple portfolios. For more complex situations, see Adjusted Cost Base Spreadsheet for Canadian Investors for a comparison of the two approaches.
myCostBase as the dedicated tracker
If your portfolio matches any of the criteria above — multiple brokerages, ETF distributions, USD trades, transfers, or years of history — this is what a dedicated tracker does instead of a spreadsheet:
Multi-brokerage pooling happens automatically. Enter transactions from Wealthsimple, Questrade, IBKR, or any other taxable account, and myCostBase keeps one weighted-average ledger per security instead of separate per-broker totals.
ETF distributions post themselves. T3 Box 42 return-of-capital amounts and reinvested capital gains distributions apply directly to the ledger, so an adjustment from three years ago doesn’t stay missed.
USD trades carry their own rate. Each transaction records its Bank of Canada rate and date, so the Canadian-dollar ACB doesn’t depend on remembering which rate you used at the time.
T5008 reconciliation runs at year-end, comparing your ledger against Box 20 for every sale before you file Schedule 3.
Everything stays in an audit trail — the record a tax preparer or CRA review would ask for, built as you go instead of reconstructed after the fact.
For the full calculation methodology and worked examples, see How to Calculate Adjusted Cost Base in Canada.
General information only — not tax, legal, or financial advice. Consult a qualified professional for advice specific to your situation.