Does buying inventory reduce your taxes? What the year-end count actually changes

Summary

The value of the goods on your shelves on the last day of your fiscal year, meaning your corporation’s year-end in whatever month it falls, is the figure that moves your corporate tax bill most. Buying more goods before that date does nothing for your income tax.

1. Money you spend on goods for resale isn’t deducted when you spend it, because the purchase swaps cash for goods you still own. You deduct what an item cost you in the year you sell it, through a calculation called cost of goods sold. Take opening stock, the dollar value of the goods you held on the first day of your fiscal year. Add what you spent on goods during the year, then subtract closing stock, the dollar value of what’s still unsold on the last day. Both stock figures are dollar amounts rather than counts of items, so you count the units and then price them.
2. Closing stock is the only figure in that calculation your count changes. Every dollar you add to it takes a dollar of deduction away, so your taxable income goes up by that dollar. Every dollar you leave out cuts your taxable income by a dollar. Miss $50,000 of goods, measured at what you paid your supplier, and you deduct an extra $50,000 this year and $50,000 less next year.
3. The Income Tax Act requires you to make a written list, once a year, of the goods you’re holding: what they are and how many of each. The Canada Revenue Agency expects you to build that list by physically counting the goods at your year-end. Stock-tracking software replaces the count only where it’s reliable and you’ve been checking it against the actual shelves.
4. Value each item you bought for resale at what it cost to get onto your shelf, which accountants call its laid-down cost. The laid-down cost is the supplier’s invoice, plus shipping, customs duty, the fee your customs broker charges to clear the goods, and storage costs where those are significant.¹ Anything you manufacture yourself carries a share of your labour and factory overhead as well.²
5. Then reduce the recorded value of the specific items genuinely worth less than you paid, which is called writing them down. Do it item by item, with evidence dated on or before your year-end. Knocking a flat percentage off the whole inventory for stock you assume has gone stale isn’t deductible.

We’d recommend working through those five steps in order every year. If you want a deduction before your year-end, it has to come from something other than stock (e.g. equipment you actually need, or a bonus to yourself).

There’s one exception worth knowing before you start. Farming and fishing businesses can elect the cash method, under which stock is deducted in the year you pay for it. A farming business then adds purchased stock still on hand back into income, to the extent of the loss.³ If that’s you, ask us before your year-end, because the five steps work differently for you.

What a count error costs

Leaving $50,000 of goods out of the count deducts an extra $50,000 of cost. Most Canadian-owned private corporations pay 9% federal tax on their first $500,000 of ordinary operating profit each year, a threshold called the small business limit. A corporation that qualifies keeps $4,500 of federal tax it would otherwise have paid this year.⁴ Your province charges its own corporate tax on the same profit, at a rate that differs by province and that several provinces changed during 2026, so the real figure is larger.

Next year’s opening figure carries the error forward, so next year’s bill is higher by the same amount and the two cancel out over the life of the business. The cash is real in the year of the error, though, and interest runs on the tax you underpaid, at the rate the CRA sets for overdue tax, until the shortfall is paid, even if you correct the mistake yourself.⁵

The count itself

The Income Tax Act requires an annual inventory as part of your records, and the regulation under it asks for the quantities and the nature of the goods, in enough detail that someone could put a value on them.⁶ The CRA’s published guidance says the count should be a physical one, carried out at the end of the year.⁷ Guidance isn’t law, but the record-keeping rule is, and a closing figure with no count behind it is one you can’t support. You can skip counting only where you run a reliable perpetual inventory system, meaning software that adds units as you receive them and removes them as you sell them. Even then, you have to have verified it periodically against the actual quantities on hand.

Cut-off means deciding which of the goods moving in or out around your year-end date were yours on the last day. Goods you already own belong in the count even if the invoice hasn’t arrived. For goods in transit, check the contract’s ownership terms alongside its delivery terms. Shipping terms describe delivery and risk, but international Incoterms don’t themselves decide when title passes.⁸ Goods a supplier left on consignment, meaning the supplier still owns them until you sell them, aren’t yours at all. A container counted on the wrong side of that line moves closing stock and taxable income by its landed cost in the same direction.

Packaging, labels, shop supplies and spare parts are inventory in their own right, so they get counted too, and a bulk buy of boxes just before your year-end isn’t a deduction this year.⁹ Keep three things afterwards: the dated count sheets, a note of who counted each area, and a worksheet showing how you priced each item. Keep them for six years from the end of the last tax year they relate to, and longer if you filed that year’s return late, if you’ve objected to an assessment or have an appeal outstanding at the Tax Court, or if the CRA has demanded it.¹⁰

Working a closing figure backwards from the profit margin you expected puts a false statement in your return. Where a false statement is made knowingly, or with carelessness bad enough to amount to the same thing (i.e. gross negligence), the penalty is the greater of $100 and 50% of the tax you understated and the credits you overstated.¹¹

Obsolete stock: writing it down

Canada gives you two ways to value what you still hold at year-end. One values the whole inventory at fair market value, and the other compares two figures for each item and takes the lower of them.¹² This section covers the second, which is what most owner-managed businesses use. The two figures for an item are what you paid for it and its fair market value at year-end, meaning what a willing buyer would pay a willing seller.

Fair market value is normally measured as what it would cost you to buy the same item today. For goods that have deteriorated so far you can’t sell them through your usual channels, use what you’d net from selling them after the costs of selling. Whichever measure you use should be the one your financial statements use, applied the same way each year.¹³

The comparison runs item by item, so where one product has fallen below cost while another has risen above it, you write the fallen one down and leave the risen one at cost.¹⁴ One exception matters if you price your stock at a weighted average, meaning you average what you paid across identical units instead of tracking each one. Where separate fair market values are known but only an average cost figure is available, the CRA directs you to compare total cost against total fair market value, and a fall on one product does then get offset by a rise on another.

A write-down has to reflect the condition of the goods on the last day of your year. A reduction for losses you expect after year-end isn’t accepted, and neither is a write-down taken to keep next year’s profit margin looking normal.¹³ Support it with an aged-stock report showing how long each line has sat unsold, a supplier price list showing replacement cost has fallen, or a markdown you ran before year-end. Evidence created afterwards still has to prove a fact about your year-end date.

Knocking a flat percentage off your inventory for stock you assume has gone stale, sometimes called an obsolescence allowance and sometimes a provision, buys you nothing. The Act denies the deduction, so the CRA adds the amount back to your taxable income for the year. You deduct the same amount the following year, but you’ll normally have booked a fresh percentage by then, so the cycle repeats and you’re never ahead.¹⁵

How often this changes

The inventory valuation rules in the Income Tax Act were last amended in 2017, and the federal bills that became law in 2026 left them alone, as far as the June 17 2026 consolidation we checked. Work back through the five steps in the summary when your business model changes (e.g. you start importing or manufacturing), or when you switch accounting or stock-tracking systems. Do it as well when prices in your category move sharply, because a falling market produces legitimate write-downs.

Closing thoughts

A closing figure worked backwards from the profit you expected, which accountants call a plugged number, is where this goes badly wrong. A plugged number leaves you nothing to argue with when the CRA questions your pricing, and it exposes the corporation to the penalty above. A real count with dated sheets gives you a position you can hold even where the CRA disagrees with how you valued a line. We’d put your effort there rather than into the choice of valuation method.

How we handle it

We set the count up with you before your year-end rather than picking through it afterwards. Practically, we agree the cut-off date, build the count sheets your staff will use, and prepare a laid-down cost worksheet that carries freight and duty into the per-unit figure. We then walk the aged-stock list with you and record the write-downs you can evidence, with the reason against each line.