Reconstructing ACB when purchase records are missing

A missing purchase confirmation does not tell you what an investment cost. It tells you that part of the evidence is missing. When reconstructing adjusted cost base in Canada, separate the search for records from the calculation itself. A current account balance, a historical share price, and a broker’s book value can each help your investigation, but they answer different questions.

This workflow is for an individual reconstructing taxable securities held as capital property. It starts with recoverable documents and ends with a record of what is verified, what is inferred, and what still needs professional review. If you simply need to organize records you already have, use the ACB recordkeeping checklist .

Build an inventory before entering numbers

List every brokerage that held the security, including closed accounts. Record the account owner, taxable status, account currency, transfer dates, security name, and any old ticker symbols. Search downloaded files, email attachments, paper statements, and records your accountant retained. Do not limit the search to the brokerage currently holding the shares.

Create a separate evidence log with columns for event date, document, quantity, amount, currency, and confidence. Mark an item as verified only when you can identify its supporting record. A note saying “probably bought in March” belongs in the investigation column, not in a finalized purchase row.

Start with the oldest available statement and compare its opening balance with what you know. If it starts with 250 shares already held, that statement does not establish the cost of those shares. It does establish a quantity checkpoint from which you can work backward.

Ask for the right archive documents

Request transaction history, trade confirmations, monthly statements, and transfer records from each institution. Specify the security, account, and date range. A generic request for a tax slip may return only sale information, leaving the acquisition gap unresolved.

For an account that moved through an in-kind brokerage transfer , ask the sending institution for the records supporting the transferred cost and ask the receiving institution what cost information it received. Keep the transfer date separate from the original acquisition dates. If a broker supplies a reconstructed figure, retain its explanation of the method and the period covered.

Issuer distribution tables help identify annual return-of-capital and reinvested-distribution amounts. They still need to be matched to your actual units and entitlement dates. A per-unit distribution history alone cannot prove how many units you held throughout the year.

Reconstruct the transaction sequence

Put verified purchases, reinvestments, adjustments, and sales in chronological order. For each step, calculate the running share balance and total ACB. Check the share balance against independent statements before relying on the resulting cost figure.

Do this across taxable accounts belonging to the same owner. A purchase found at an old brokerage may change the pooled cost used for a later sale at your current institution. Preserve separate account references even though the tax calculation combines identical property.

Historical price charts are useful for plausibility checks, but avoid treating the closing price as proof of an execution. The trade may have occurred at another price, involved a commission, or been a transfer rather than a purchase. If the actual cost remains unresolved, document the gap and get advice on an appropriate evidentiary approach.

Worked reconstruction with recovered statements

Suppose your recovered records establish these events for one Canadian-dollar ETF. There are no other holdings or adjustments in this example.

The cost per unit before sale is $6,250 ÷ 150, or $41.6666667. A sale of 60 units at $50 produces $3,000 of gross proceeds. With a $10 selling commission, the capital gain is $3,000 − $2,500 − $10 = $490. The remaining 90 units have total ACB of $3,750.

The result is supported because each input was recovered. If the second purchase were still missing, the same arithmetic would be only a scenario. Save the completed worksheet and its document references together. Use the worked ACB calculation guide to check the arithmetic after recovering the inputs.

Common reconstruction mistakes

Do not insert today’s market value as the opening ACB just to remove an error message. Do not use zero automatically because a transfer arrived with a blank cost field. Both choices replace an evidence problem with an unsupported tax input.

Watch for duplicates when combining a yearly CSV with monthly statements. A DRIP may appear as a cash distribution and a purchase; importing both as purchases inflates cost. A transfer may appear on both sides of the move but should not double the taxpayer’s holding.

Also check split factors. If a statement shows twice as many shares after a split, that does not establish a second purchase. Reconcile the quantity change before interpreting a later price or sale.

Document the conclusion and remaining uncertainty

CRA’s capital gains guide describes the acquisition and disposition records needed to support a calculation. Keep original files, the reconstructed ledger, correspondence with brokers, and a short explanation of each correction. Retain acquisition evidence while it remains relevant to a future disposition; an old purchase is not irrelevant simply because it happened many years ago.

Use a review sheet with three outcomes: supported, awaiting documents, or referred for advice. Identify the amount affected by each unresolved item and which filed or future sale it could change. This lets a tax professional focus on the consequential gaps instead of repeating the entire search.

If the reconstruction changes a previously filed gain, review the affected return and the applicable correction process. Do not silently replace a historical figure without keeping the earlier version and explaining why it changed. Once the opening history is supported, update the ledger as new events occur so the same search is not needed again.