What Interactive Brokers provides
Interactive Brokers (IBKR) offers detailed activity and tax reports, including flexible custom statements you can export for a full transaction history. For non-registered accounts you’ll generally receive a T5008 covering your dispositions, along with T3 and T5 slips for distributions and dividends. Trades inside a TFSA or RRSP aren’t reported and aren’t taxable.
Why the cost base may be incomplete
Like every broker, Interactive Brokers can only compute cost base from activity it sees in your Interactive Brokers accounts. If you transferred shares in, hold the same security at another broker, reinvested distributions, or received equity-comp shares, its cost figure can be partial or blank — while the proceeds are usually reliable.
A Interactive Brokers detail worth knowing
IBKR is multi-currency and global by design. Trades can settle in many currencies, so converting every disposition to Canadian dollars at the right date is essential — and easy to get wrong at volume.
Getting your data into shape
Export your Interactive Brokers activity (transactions and slips), then build a pooled cost base across all your accounts and brokers — applying reinvested distributions, return of capital, FX on US trades, and any corporate actions. That reconciled ACB, not the raw slip, is what belongs on your Schedule 3.