ACB Tracker for Canadian Investors

Adjusted cost base (ACB) tracking is the record-keeping obligation that Canadian investors carry for every security in a taxable account. The CRA requires investors to maintain a running ledger of the weighted average cost per share across all non-registered accounts — and to report capital gains based on that figure, not the cost your broker shows.

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:

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 shows book value: the average cost of shares purchased within that one account. This is useful for tracking unrealized gains in a single account, but it is not the adjusted cost base that the CRA requires.

The gap between broker book value and legal ACB grows whenever:

• You hold the same security at more than one taxable brokerage
• You transferred shares between brokerages (the receiving broker may book at market value, not original cost)
• 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.

Example:

• 200 shares of XEI.TO purchased at Questrade — average cost $21.50/share
• 100 shares of XEI.TO purchased at Wealthsimple — average cost $23.80/share

Questrade’s book value: $21.50/share
Wealthsimple’s book value: $23.80/share
Legal ACB required by CRA: (200 × $21.50 + 100 × $23.80) ÷ 300 = $22.27/share

If you sell 50 shares at Wealthsimple and use Wealthsimple’s $23.80 figure, you report a capital gain of $0.50/share × 50 = $25.00. Using the correct pooled ACB of $22.27, the gain is $1.53/share × 50 = $76.50. The difference compounds across a portfolio of multiple positions.

For more on the pooling requirement, 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 US-listed stock or ETF in a Canadian taxable account, you must record the ACB in Canadian dollars using the Bank of Canada daily exchange rate on the trade date — not the rate your broker applied, not the monthly average, and not the rate on the settlement date.

On a CAD-denominated ACB, you apply the same pooled weighted average as for CAD securities. When you sell, you convert the proceeds at the Bank of Canada rate on the sale date, then apply the CAD ACB to calculate the capital gain.

IBKR users should be particularly careful here: IBKR’s internal FX rates and mark-to-market accounting do not align with CRA’s weighted-average cost method. For a complete breakdown of IBKR-specific ACB issues, see Broker Book Value vs Adjusted Cost Base in Canada.

T5008 reconciliation as part of ACB tracking

Each tax year, your broker issues a T5008 for each security you sold. Box 20 is the broker’s book value. Box 21 is the proceeds.

A complete ACB tracking workflow includes reconciling Box 20 against your own ACB ledger before you file Schedule 3. If they differ — which they often do for multi-brokerage investors or ETF holders — you use your ACB, not Box 20. Keeping a record of the reconciliation protects you in the event of a CRA reassessment.

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 becomes necessary 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.

How myCostBase works as an ACB tracker

myCostBase is designed around the specific requirements of Canadian ACB tracking — not a generic cost-basis tool adapted for Canada:

Multi-brokerage pooling: Enter transactions from Wealthsimple, Questrade, IBKR, and any other taxable account. myCostBase automatically pools identical securities across all accounts into the single weighted-average ledger that CRA requires.

ETF distribution adjustments: Apply T3 Box 42 return-of-capital amounts and reinvested capital gains distributions (phantom income) directly in the transaction ledger. The system updates the ACB pool automatically.

Bank of Canada FX conversion: For USD transactions, enter the trade-date Bank of Canada rate. myCostBase tracks the CAD-equivalent ACB throughout the life of the position.

T5008 reconciliation: At tax time, compare your myCostBase ACB against T5008 Box 20 for each sale. Export the ledger for your records or your tax preparer.

Audit trail: Every transaction and adjustment is logged with date, amount, and resulting ACB per share — giving you the documentation CRA would request in a capital gains review.

For the full calculation methodology and worked examples, see How to Calculate Adjusted Cost Base in Canada.

This page is for general educational purposes only and is not tax, legal, or financial advice. Adjusted cost base calculations depend on your complete transaction history and personal circumstances. Consult a qualified tax professional for advice specific to your situation.