If you sold or redeemed securities during the year, your broker or financial institution sends you a T5008. It is a record of what you were paid, not a calculation of what you gained — and that distinction is the whole point of this article.
You do not prepare it. You receive it and use it when you file.
What it reports
The T5008, Statement of Securities Transactions, reports the amount paid or credited to you for securities you disposed of or redeemed during the year. These transactions may be on account of income or capital. Interpretation Bulletin IT-479, Transactions in Securities, sets out how that distinction works.
Who sends it
Financial institutions, and traders or dealers in securities.
Where the transactions go
If you are an individual having to file a T1 return, report transactions on account of capital on Schedule 3.
You can report transactions on account of income either as business income, on line 13500 of your return, or — for debt obligations in bearer form — as investment income, on line 12100.
Box 20 does not always give you the answer
This is the box worth slowing down for. The amount in box 20 may or may not reflect your adjusted cost base (ACB) for the purpose of determining the gain or loss from the disposition of the security.
You are required to make the adjustments, as needed, to the amount indicated in box 20 at the time of determining and reporting your gain or loss from the disposition. In other words, the slip is your institution's record of a cost or book value, and it is not necessarily the figure the return needs.
The CRA page this article is written from explains only box 20. For the other boxes it points to Interpretation Bulletin IT-479, so this article does not put meanings on them.
Quebec residents and consolidated slips
Since the 2021 taxation year, financial institutions, traders or dealers in securities can send recipients who reside in Quebec a consolidated T5008/RL-18 slip for all transactions. Review each page carefully: the transactions to be reported are located starting from page 3.
If a slip is late or looks wrong
The institution that issued the slip is the one to ask about it. The Canada Revenue Agency (CRA) page this article is written from does not state a date by which the slip has to reach you.
What to keep
Keep the slip, and keep it with whatever establishes your adjusted cost base: purchase confirmations, records of reinvested distributions, notes on transfers between accounts. Box 20 is a starting point, and the records behind it are what let you adjust it.
Keep every page of a consolidated slip. On a T5008/RL-18 the reportable transactions start partway through the document, and a first page on its own is not the slip.
Dossier stores the slip and identifies it as a T5008, so it is with the rest of your year's paper. It does not read the amounts off it, and it does not work out an adjusted cost base or decide whether a transaction is on account of income or capital; those are settled when you file.
Official CRA sources
Source: Canada Revenue Agency (canada.ca). Not tax advice.