Adjusted Cost Base Canada 2026: How to Track ACB on Your ETFs

Adjusted cost base (ACB) is the total cost of an investment for tax purposes, and tracking it correctly keeps your capital gains tax accurate when you sell. For ETFs in a non-registered account, ACB changes over time as you buy more units, reinvest distributions and receive return of capital. Your broker’s number is a starting point, but it can be wrong after transfers or special distributions. This guide explains how the CRA defines ACB, how to calculate it for ETFs, which distributions raise or lower it, and a simple routine to keep your records right in 2026.

Quick Answer

• ACB is what you paid for an investment, including commissions, adjusted for certain events over time.
• For identical units, the CRA uses average cost: total ACB divided by units held, across all your non-registered accounts.
• Reinvested distributions and reinvested (“phantom”) capital gains raise ACB; return of capital lowers it.
• ACB only matters in non-registered accounts. Sales inside a TFSA, RRSP or FHSA aren’t reported.

What Is Adjusted Cost Base?

The CRA describes adjusted cost base as the cost of a property plus any expenses to acquire it, such as commissions and legal fees. When you sell, your capital gain or loss is the proceeds of disposition minus the ACB and any outlays and expenses of the sale. If your ACB is too low, you overpay tax; if it’s too high, you underreport your gain.

ACB matters only when the investment is in a non-registered account. Gains in a TFSA are tax-free, and RRSP withdrawals are taxed as income regardless of any gain, so you don’t need to track ACB inside those accounts. If you’re deciding where to hold investments, our guide to registered accounts in Canada covers the options.

Average cost for identical units

Most investors buy the same ETF several times. Under the CRA’s rules for identical properties, you recalculate an average cost each time you buy. You don’t get to pick which units you sold. The ACB per unit is the total ACB of all identical units divided by the number you own.

How Do You Calculate ACB on an ETF?

Here’s a simple example with round numbers. Commissions are included in the cost.

When you sell 60 units, their ACB is 60 times the $21.40 average, or $1,284. If you received $1,500 after commission, your capital gain is $216, and half of that, $108, is taxable. Selling doesn’t change the ACB per unit of what’s left; it only reduces the total.

Adding year-end adjustments

Now say the ETF reports two items on your T3 slip for the 90 units you still hold:

If you later sold all 90 units for $2,160, your gain would be $207. Without the adjustments, you’d have reported $234, paying tax again on the $45 you were already taxed on and missing the $18 reduction.

Tracking foreign-currency ETFs

For US-listed ETFs, ACB must be in Canadian dollars. Convert each purchase, sale and reinvested distribution at the exchange rate for that day, such as the Bank of Canada rate, and note the rate you used. Exchange-rate changes can create a gain or loss even if the US-dollar price didn’t move.

Distributions That Change ACB

ETFs pay different kinds of distributions, and they affect ACB differently. The CRA’s guidance on mutual fund units sets out the general approach.

Reinvested distributions

If distributions are reinvested to buy more units, those units are purchases. Add the reinvested amount to your total ACB and the new units to your unit count. This matters because you’ve already paid tax on the distribution; if you forget to add it, you’ll be taxed on it again when you sell.

Reinvested capital gains distributions

Many ETFs make a year-end capital gains distribution that’s paid in new units and then consolidated, so your unit count doesn’t change. You still report the distribution as income from your T3 slip, and you add it to your ACB. Brokers often miss this one.

Return of capital

Return of capital gives you back part of your own money. It isn’t taxed when you receive it, but it reduces your ACB. On a T3 slip, it’s shown in box 42. If your ACB would go below zero, the negative amount is treated as a capital gain in that year and your ACB is reset to zero.

ACB on Other Investment Types

ACB applies to any capital property in a non-registered account. The basics are the same; the details differ.

Common ACB Issues to Check

Your broker’s ACB is often a reasonable estimate, but it isn’t the official number. You’re responsible for what you report. Watch for:

• Account transfers. When you move investments between brokers, the cost history doesn’t always come with them, and the new broker may show the market value on the transfer date as book value.
• The same ETF in two accounts. If you hold the same ETF in two non-registered accounts, the average cost rule applies across both, not to each account separately.
• Year-end distributions. Many brokers can’t update ACB for phantom distributions until T3 slips are issued in the spring, usually by the end of March.
• Superficial losses. If you sell at a loss and you or an affiliated person, such as your spouse, buy the same property within 30 days before or after, the loss is denied and added to the ACB of the replacement units. See our guide to rebalancing without capital gains.
• Gifts and inheritances. Property you receive generally has an ACB equal to its fair market value when you got it, not what the previous owner paid. Transfers from a spouse are an exception, because they normally keep the original cost.

Pro Tip: Many ETF providers publish each fund’s annual distribution breakdown, including reinvested capital gains and return of capital, in January or February, before T3 slips arrive. Bookmark the tax information page for each ETF you hold and update your spreadsheet once a year from it.

Why ACB Matters at Tax Time

Each sale in a non-registered account is reported on Schedule 3 of your return, using the proceeds, the ACB and any outlays and expenses. You report the gain or loss in the year you sell. Your broker’s T5008 slip shows the proceeds and may show cost, but the cost figure can be blank or wrong.

Using T5008 slips

Treat the cost on a T5008 as a starting point only. If your own records give a different ACB, report the figure you can support with documents, and keep your calculation in case the CRA asks how you arrived at it. A gap often shows up after a year with large reinvested capital gains distributions, which is a sign to review the numbers.

Planning ahead

Accurate ACB records also help with decisions before you sell. Knowing which holdings have large gains and which have losses lets you plan withdrawals, rebalancing and tax-loss selling to keep your tax bill under control. It also helps when you donate securities to charity, because the gain on the donated units is still calculated from ACB, even though it may be taxed at zero.

A Simple ACB Tracking Routine

1. Start a spreadsheet for each ETF. Record the date, event, units, amount in Canadian dollars, total ACB and ACB per unit.
2. Log every trade. Add each purchase and sale, including commissions, as soon as it happens.
3. Add reinvested distributions. Use monthly or quarterly statements to log reinvested amounts and new units.
4. Update after the year-end tax data arrives. Add reinvested capital gains and subtract return of capital from T3 box 42 or the provider’s tax notice.
5. Compare with your broker. If your figure differs from the broker’s, find out why before you file.
6. Keep records. Save trade confirmations, statements and T3 slips while you own the investment, and for at least six years after the tax year you sell.

Free online ACB calculators and spreadsheet templates can do the averaging for you, but they’re only as accurate as the transactions you enter.

Key Takeaways

• ACB is your total cost for tax purposes, including commissions, and it only matters in non-registered accounts.
• For identical units, the CRA uses average cost across all your non-registered accounts.
• Reinvested distributions and reinvested capital gains distributions increase ACB; skipping them means paying tax twice.
• Return of capital, shown in T3 box 42, reduces ACB, and a negative ACB is taxed as a capital gain right away.
• Broker ACB figures can be wrong after transfers or year-end distributions, so check them before you file.
• A simple spreadsheet updated after each trade and each year’s tax data keeps your ACB accurate.

Frequently Asked Questions

Is my broker’s book value the same as ACB?

Not always. Book value is often close to ACB, but it may miss reinvested capital gains, return of capital or cost history from a transferred account. You’re responsible for the figure you report, so check it.

Do I need to track ACB in a TFSA or RRSP?

No. Capital gains and losses inside registered accounts aren’t reported on your return, so ACB doesn’t affect your taxes there.

Does a stock split change my ACB?

A split changes the number of shares you own but not your total ACB. Your ACB per share goes down in proportion to the split. Record the new unit count and per-unit figure.

How long should I keep ACB records?

Keep them for as long as you own the investment, and then for at least six years after the end of the tax year in which you sell, since the CRA can generally review your return during that period. Because ACB builds over many years, old purchase records still matter when you finally sell.

What if my ACB goes below zero?

If return of capital reduces your ACB below zero, the negative amount is treated as a capital gain in that year, and your ACB becomes zero. Later return of capital creates further capital gains until you sell.

Conclusion

Tracking adjusted cost base takes a few minutes per trade, but it can stop you paying tax twice on the same income. Use average cost for identical ETF units, add reinvested distributions and capital gains, subtract return of capital, and compare your numbers with your broker’s before filing. A simple spreadsheet and your T3 slips are usually all you need. Accurate records also make tax-loss selling and rebalancing easier when the time comes.

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Official sources: CRA: Capital gains definitions (adjusted cost base); CRA: Identical properties; CRA: Mutual fund units and distributions; CRA Guide T4037, Capital Gains.