What your business uses up doing the work is deductible in the year you buy it. On Form T2125, it goes on line 8811, Office stationery and supplies.
Despite the name, this is the working-supplies line, not the desk-drawer one.
What belongs here
The cost of items the business used to provide goods or services. The CRA's own examples:
- drugs and medication used by a veterinarian
- cleaning supplies used by a plumber
If you run a daycare, these include household supplies that children use and food you buy to feed the children.
What does not belong here
Small general office items. Pens, stamps, and paper clips are office expenses and go on line 8810.
Goods you bought to resell, or materials that become part of what you sell. Those join your purchases in cost of goods sold, in Part 3 of the form, rather than sitting among your expenses.
Lasting tools and equipment. These are capital property, and their cost comes off over several years through capital cost allowance (CCA) instead of all at once here.
What to keep
Keep a record of all your income and expenses, with the documents behind them. The receipt should show the seller, the date, and what was bought — and on this line the what is the part that matters, because it is the item's use in your work that puts it here.
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.