MyCostBase is built around one job: maintain a reviewable adjusted cost base ledger for Canadian taxable accounts. The product keeps the raw transaction trail, calculates the numbers that change over time, and surfaces warnings when the available data is not good enough to trust silently.
One pooled ACB across all taxable accounts
Canadian ACB rules apply across the tax owner’s non-registered accounts, not per broker login. MyCostBase combines holdings for the same identical property into one weighted-average ACB pool so a buy at one brokerage and a sell at another still roll into the same ledger.
Registered accounts such as RRSP, TFSA, FHSA, and RESP stay outside the pool. That distinction is part of setup because it changes the legal calculation, not just the dashboard view.
Import history or enter it manually
MyCostBase supports the transaction types investors actually need to maintain over time:
- buys and sells;
- DRIP purchases;
- return of capital adjustments;
- reinvested capital gain distributions;
- stock splits;
- transfer in and transfer out events;
- manual corrections with a required note.
For broker imports, the goal is not just to ingest rows. The system flags duplicate rows, unknown securities, missing FX rates, and transfers where the original basis is not yet known. That keeps the ledger honest instead of quietly absorbing bad source data.
Date-based FX conversion for USD transactions
Foreign-currency trades need CAD values on the transaction date. MyCostBase uses Bank of Canada daily rates, records the rate source alongside the row, and falls back consistently when the requested date is a weekend or holiday.
If you need to use a different documented rate, you can override it and keep the note with the transaction. The override becomes part of the audit trail rather than an off-platform spreadsheet fix no one can trace later.
Security ledgers that explain the number
Every security has a chronological ledger showing the running share count, total ACB, ACB per share, and realized gain or loss after each event. The point is not just to output the final number. The point is to let you inspect where that number came from.
That matters when you need to answer questions like:
- why ACB dropped after an ETF tax slip;
- which transfer carried the basis forward;
- which FX rate was used for a USD sale;
- whether a manual adjustment happened before or after a disposition.
Warnings when the system should not pretend certainty
MyCostBase does not try to look smarter than the available data. If a transfer basis is missing, a security needs confirmation, or a superficial loss case may require manual review, the product warns you directly instead of producing a clean-looking but unsupported number.
That is especially important for cross-account histories where the risk is not a calculation bug. The risk is assuming the source data was complete when it was not.
Reconciliation and export for tax prep
The year-end workflow is built around the actual handoff investors need:
- compare broker or T5008 figures with MyCostBase figures;
- inspect the difference at the security level;
- explain likely causes such as missing ETF adjustments, pooled holdings across brokerages, or transfer basis errors;
- export capital gains summaries, disposition detail, and full audit trails.
MyCostBase does not replace tax filing software. It supplies the upstream ACB and gain/loss work those filing tools still expect you to know already.
Built for Canadian investors with real ledger complexity
The product is a fit when you hold stocks or ETFs in one or more taxable accounts and need more than a simple broker book value column. It is especially useful if you have USD trades, transferred positions, DRIP activity, ETF distributions, or year-end T5008 mismatches.
If you want the step-by-step workflow, read How It Works. If you want implementation details, start with Getting Started and Importing Transactions.