If you’re an Amazon or Shopify seller, an importer, or run a small manufacturing business, here’s the honest answer: usually, no, not right when you buy it. Even with the friendlier rules small businesses get in 2026, you generally still deduct inventory costs when you sell the item, not when you pay for it. There is a real exception that makes life easier for small businesses, but it doesn’t work the way most people assume. That gap between what people think the rule says and what it actually says is where a lot of online sellers get into trouble.
The Basic Rule: You Deduct Inventory When You Sell It, Not When You Buy It
Here’s the general rule the IRS uses: if your business buys, makes, or sells physical products, you normally have to track that inventory and treat it as an asset (not an expense) until it actually sells. Think of it like this: the cost of the product sits on your books the same way a piece of equipment would, and it only becomes a deduction once the item leaves your shelf and goes to a customer.
Say you spend $50,000 on inventory in November and none of it sells before the end of the year. Under the basic rule, none of that $50,000 is deductible for that year, even though the money is already out of your bank account. This trips up a lot of new e-commerce sellers. You can have a great cash-flow month and still get hit with a tax bill that doesn’t match how your bank balance looked.
The Small Business Break — What It Really Does
There’s a rule, Section 471(c), that lets smaller businesses skip some of this complexity. For 2026, you qualify if your average revenue over the last three years is $32 million or less, and you’re not part of a narrow category of partnerships built mainly to pass losses to outside investors.
If you qualify, you get to pick one of two simpler approaches:
Option 1: treat your inventory like supplies instead of formal inventory. This is the option most small sellers pick, and it’s also the one people misunderstand most. Here’s what it actually does: your inventory becomes deductible whichever comes later — the year you pay for it, or the year you actually sell it to a customer. So if you buy something in November and pay for it right away, but don’t sell it until February, you still don’t get the deduction until February. This option skips a lot of the paperwork and formal cost-tracking that used to be required, but it does not let you write off a warehouse full of unsold stock on December 31.
Option 2: just follow whatever your bookkeeping already shows. If you have audited financial statements, you follow whatever method those statements use. If you don’t, you can instead follow whatever your regular bookkeeping (QuickBooks, Xero, whatever you use) already shows, as long as it’s done consistently and reflects how you actually run the business, not just a number picked at tax time to look better.
Neither option means “deduct it the moment you buy it.” Both still generally tie the deduction to when you sell the item; they just cut down on the extra paperwork and formal cost-allocation work that would otherwise be required.
The Trap Most Online Sellers Don’t See Coming
Here’s the part that catches a lot of Amazon sellers, Shopify merchants, and small importers off guard.
Most online sellers run their books through QuickBooks Online, Xero, or some kind of e-commerce accounting tool, often connected through an add-on like A2X or a similar inventory app. By default, these tools already treat inventory as an asset and automatically calculate your cost of sales every time something sells. That setup is, in the eyes of the IRS, already a real accounting method —the “follow your bookkeeping” option described above— whether or not you or your accountant ever consciously chose it.
And here’s why that matters: once your books are actually working that way, that’s your official method for tax purposes, even if nobody ever sat down and made a formal decision about it. If you want to switch to a different approach later, you can’t just do that on your tax return if your own accounting software has been treating those same purchases as inventory the whole time. You need IRS approval first. Mixing the two —one method quietly running in your books, a different one showing up on your return— is exactly the kind of thing that can draw unwanted attention if the IRS ever looks closely, and it also means your return may not reflect your actual financial picture.
How to Actually Switch Methods
Want to change how your business handles inventory? Maybe you want to switch to the simpler “treat it like supplies” option. Maybe you want to stop following your books and pick a different approach. Or maybe you just noticed a mismatch between your books and your tax return and want to fix it.
Whatever the reason, this counts as a change in accounting method. You can’t just fix it by amending an old return. Instead, there is Form 3115 made exactly for this situation.
A few things worth knowing going in:
- Switching to the simpler “treat inventory like supplies” method for the first time often comes with a one-time adjustment tied to whatever inventory you’re currently holding. Depending on your situation, this can actually create a nice one-time deduction rather than a cost, which is a good reason to look into this proactively instead of waiting until something feels off.
- Most small businesses making this kind of change qualify for a streamlined process with no filing fee; but it still has to be done correctly, and in the right year.
- These changes generally apply going forward, not backward. You’re fixing how future years are handled, not rewriting old returns which is also why catching a mismatch early saves you more than catching it three years later.
Which Method Is Your Business Actually Using? Check These 5 Things
Before assuming you know the answer, it’s worth checking for real. Go through these five questions:
- Software Check
Does your accounting or inventory software automatically treat inventory as an asset and calculate your cost of sales when items sell? If your Shopify, Amazon, or point-of-sale setup feeds into QuickBooks, Xero, or a dedicated inventory tool that does this, that’s a real accounting method already in place — not just a bookkeeping habit. - Balance Sheet Check
Does your balance sheet show an inventory number that isn’t zero? If yes; you, your bookkeeper, or your software has already made a choice about how to handle this, whether anyone meant to or not. - Form 3115
Has anyone ever filed the IRS form for this (Form 3115), or written down which method your business is actually using? If you’re not sure, there’s a real chance your books and your tax return have drifted apart without anyone noticing. - Revenue Threshold
Is your average revenue over the last three years under $32 million? If you’re close to that number, or growing fast toward it, whether you even qualify for these simpler rules could change from year to year. - Platform Switch Impact
If you’ve switched software, platforms, or bookkeepers recently, did your inventory treatment change with it — and was that ever addressed on a tax return? New software often comes with different default settings, and that alone can quietly shift your method without anyone treating it as the real event it is.
If your answer to any of these is “I’m not sure,” that’s not a small detail — that uncertainty is the actual issue worth looking into.
Key Takeaway
The small business inventory rule genuinely makes things easier, but it was never meant to let you deduct a big inventory purchase the moment you pay for it. What it really does is cut down on paperwork for businesses that qualify — as long as everyone actually knows which method the business is using, and it was set up correctly in the first place.
For Amazon sellers, Shopify merchants, importers, and small manufacturers running typical e-commerce accounting setups, the real risk usually isn’t the inventory rule itself; it’s not knowing which method your own books have already put you on. At Manay CPA, we help clients figure that out, and where a change makes sense, we handle the entire Form 3115 process for you, start to finish.
Sources
Cornell Law School, Legal Information Institute | 26 U.S. Code § 471 — General Rule for Inventories
Cornell Law School, Legal Information Institute | 26 CFR § 1.471-1 — Need for Inventories
Internal Revenue Service (IRS) | Revenue Procedure 2025-32, 2026 Inflation-Adjusted Items
Internal Revenue Service (IRS) | Instructions for Form 3115 (12/2022)
