Some things you buy for the business last for years, so their cost comes off over years rather than all at once. That yearly deduction is capital cost allowance (CCA), and on Form T2125 it goes on line 9936.
What belongs here
You might acquire a depreciable property — a building, furniture, a motor vehicle, or equipment — to use in your business or professional activities. These properties wear out or become obsolete over time, so you deduct their cost over a period of several years.
The amount on this line isn't taken from a receipt. It is calculated in Area A of the form, class by class, from the depreciable property you own and what you added or disposed of during the year.
What does not belong here
The purchase price in the year you bought it. You cannot deduct the cost of a depreciable property when you calculate your net business or professional income for the year. That is precisely what CCA replaces.
The home-office share. CCA on a workspace in your home is carried inside the business-use-of-home calculation instead. The CRA warns about claiming CCA on your home; its pages explain why before you decide.
The personal-use share of anything. Only the part of an asset used to earn business income supports a claim.
Choices and consequences
You do not have to claim the maximum. Any amount up to the maximum is allowed, including nothing at all.
The first year is usually smaller. The half-year rule generally limits the claim on net additions in the year you buy something. Accelerated investment rules, and separate rules for zero-emission vehicles, change the first-year treatment for eligible property — worth reading the CRA's CCA pages before filing if you bought something substantial.
Selling changes things. When you dispose of a property, the class balance may produce recapture — an amount added back to income — or a terminal loss, an amount deducted, depending on what is left in the class.
None of this is decided on the receipt. It is worked out from the capital-asset schedule when you file.
What to keep
Keep the purchase invoice for every depreciable property, showing the seller, the date, and what was bought. That invoice is what supports the addition to a class in Area A. Do the same for anything you sell or scrap during the year, since a disposition changes the class balance.
Keep a record of all your income and expenses with the documents behind them. Don't send them in with your return. Keep them in case the Canada Revenue Agency (CRA) asks to see them. Business records follow the same six-year retention rule as your personal documents.
Official CRA sources
Source: Canada Revenue Agency (canada.ca). Not tax advice.