From T5008 slips to Schedule 3

A T5008 slip supplies transaction information, but it does not remove the need to calculate a supported capital gain or loss. Before carrying figures into Schedule 3, reconcile the sale proceeds, adjusted cost base, expenses, and currency. A reliable workflow connects each reported disposition to the ledger and the evidence behind it.

This walkthrough is for an individual reporting ordinary securities held as capital property in taxable accounts. It does not cover business trading income, special exemptions, principal residences, or every part of Schedule 3. Use the form and instructions for the actual tax year; section labels and software screens can change.

Gather the sale records first

Collect T5008 slips, trading summaries, sale confirmations, and the ACB ledger covering each disposed security. Include records from every taxable brokerage that contributes to the same owner’s identical-property pool. Keep amended slips clearly marked so you do not report both the original and its replacement.

Build a worksheet with security, quantity sold, disposition date, currency, gross proceeds, allocated ACB, selling expenses, and gain or loss. Add a source reference for each row. The worksheet is the bridge between brokerage documents and the return, rather than a second unconnected calculation.

Review dispositions that may not have an ordinary sale slip, including certain in-kind contributions or gifts. Conversely, do not treat every account movement as a taxable sale. Resolve the transaction type before copying a cash or market-value figure into the proceeds column.

Reconcile Boxes 20 and 21

Box 20 reports cost or book value; CRA warns that it may or may not reflect ACB. Compare it with the cost allocated from your supported ledger rather than assuming it must be either right or wrong. Explain material differences with transaction evidence.

Box 21 reports proceeds of disposition or settlement amount. Check the slip and trade confirmation to establish how commissions were treated. If the amount you use is already net of selling expenses, do not deduct those same expenses again in another field.

For a focused check, use the T5008 reconciliation tool . Read the Box 20 and Box 21 guide when the two fields or the broker’s terminology are unclear. The objective is a supported disposition calculation, not forcing the ledger to match a slip at all costs.

Worked example: one partial sale

Assume your complete taxable pool contains 200 shares with total ACB of $8,400 immediately before a sale. You sell 75 shares for $3,750 and pay a $10 selling commission. All amounts are Canadian dollars, and there are no loss restrictions or other adjustments.

The pooled ACB per share is $8,400 ÷ 200 = $42. The cost allocated to the 75 shares is $3,150. Using gross proceeds and a separate expense gives:

$3,750 − $3,150 − $10 = $590 capital gain.

Suppose Box 20 shows $3,000. The $150 difference needs an explanation from your records, such as an outside purchase or a supported adjustment. It is not an additional expense to subtract. Your gain remains $590 if the $3,150 allocated ACB is the supported figure.

After the sale, the remaining 125 shares carry total ACB of $5,250. Keep that closing balance for future transactions; the filing worksheet should reconcile back to the ongoing ledger rather than consume the whole holding’s cost.

Enter the disposition once

Use the publicly traded shares and other applicable securities area of the tax-year Schedule 3, or the equivalent workflow in your filing software. Enter the security details, proceeds, ACB, and expenses in the fields requested. Review the software’s generated schedule to confirm the arithmetic.

If the software imported a T5008, inspect the entry before adding your worksheet separately. You may need to correct or complete the imported entry, rather than create a second disposition. An imported slip and a manually entered sale describing the same event can double the gain or proceeds.

Do not reduce every proceeds or ACB field by the inclusion rate. Schedule 3 first calculates capital gains and losses, and its later steps determine the taxable amount. Under currently enacted section 38, the ordinary inclusion rate is one-half. The $590 example would contribute $295 of taxable capital gain if considered alone, but other gains, losses, and applicable rules affect the return’s final total.

Review slip distributions separately

A T3 or T5 capital-gain distribution is not necessarily another sale of your units. Follow the applicable tax-year instructions for reporting the slip amount. At the same time, determine whether any reinvested distribution changes the ACB carried in the ledger.

This creates two related records: the income or gain reported from the slip and the supported cost adjustment for future dispositions. Recording one does not automatically complete the other. Do not count an ordinary sale twice merely because it also appears in a trading summary.

Return of capital is another distinct adjustment. Apply supported reductions in the correct chronology before calculating the cost allocated to a sale. If an adjustment arrives late, review whether it changes the current worksheet or an earlier return rather than attaching it arbitrarily to the next year.

Common filing mistakes

Watch for foreign-currency amounts entered as though they were CAD; convert each purchase and sale at a documented rate such as the Bank of Canada daily rate . Preserve purchase and sale conversions separately; translating only a foreign-currency profit can miss the Canadian-dollar result. Also verify whether your worksheet uses gross or net proceeds consistently across institutions.

Do not deduct the whole security pool’s ACB on a partial sale. Do not automatically claim a loss before checking superficial-loss or direct registered-plan contribution restrictions. Do not treat the tax estimate from a calculator as the amount to enter in the capital-gain field.

The capital gains tax estimator can illustrate an additional-tax scenario after the gain is established. It does not prepare a complete return or replace Schedule 3’s loss, exemption, and other reporting steps.

Keep a filing reconciliation package

Save the final disposition worksheet, supporting ledger, slips, confirmations, fee explanations, and currency sources. Include a short note for each corrected Box 20 amount and retain the version actually used for filing. This makes it possible to answer a later question without guessing which spreadsheet was final.

Before submitting, compare the number of sales and total proceeds in the return with the worksheet. Investigate duplicates, missing rows, amended slips, and unexpected negative quantities. Use the Canadian ACB checklist for a broader review of the evidence and remaining holdings.

myCostBase can help organize ledger and reporting records, but filing happens in your chosen tax software or through your preparer. The final handoff should make every number traceable and every unresolved issue visible before the return is sent.