Your adjusted cost base (ACB) is the total amount you paid to acquire an investment, adjusted for certain costs and events. To calculate your capital gain when you sell, you subtract your ACB from the sale price. Keeping accurate ACB records is essential because the CRA relies on them to verify your capital gains calculations, and errors can lead to reassessments or penalties. ACB is the foundation of capital gains tax in Canada. Without it, you cannot accurately report whether you've made a profit or loss on an investment. The CRA expects you to maintain detailed records for all purchases, sales, and adjustments to support your tax filings. When you sell an investment, your taxable capital gain is calculated as: Sale Price - Adjusted Cost Base = Capital Gain Only 50% of your capital gain is included in your taxable income for 2026 (the "inclusion rate"). If you underestimate your ACB, you'll overstate your gain and pay more tax than you owe. Conversely, if you overstate your ACB, you risk an audit. Your ACB isn't just the purchase price.
Adjusted cost base (ACB) is the total cost of acquiring an investment, including purchase price and fees. It matters because capital gain tax is calculated by subtracting ACB from your sale price. If your ACB is wrong, your taxable gain will be wrong.
No, you don't file ACB details with your return. However, the CRA expects you to keep complete records (purchase confirmations, fees, corporate actions) to support your calculations if you're audited.
Use the average cost method: divide your total amount spent (including fees) by the total number of units. When you sell, apply this per-unit cost to the number of units you're selling.
ACB rules apply to investments in all accounts, including registered accounts. However, capital gains in TFSAs and RRSPs are not taxed, so ACB mainly matters if you need to track cost for other reasons like adjusting contributions.
You can add purchase price, commissions, brokerage fees, and transaction costs. You cannot add investment advice fees or accounting fees to track investments; those are claimed separately as carrying charges if eligible.