How to Deduct Non-Incidental Materials and Supplies

To deduct non-incidental materials and supplies, you claim the cost as an ordinary business expense in the tax year you first use or consume the item, not the year you paid for it. Buy $50,000 of specialty lubricants in November, use $15,000 by December 31, and only $15,000 is deductible that year. The remaining $35,000 stays on your books as an asset until it is actually used. That consumption-based timing rule comes from Treasury Regulation 1.162-3 and is what makes these supplies behave differently from most other business expenses.¹

What Makes Supplies Non-Incidental

The label has nothing to do with cost. It turns on whether you track the item.

Incidental supplies are items you keep on hand without recording how much you use and without taking a physical inventory at the start and end of the year. Printer paper, pens, cleaning rags bought in small quantities. Because no one is measuring consumption, you can deduct these when you pay for them, provided that treatment clearly reflects income.

Non-incidental supplies are the ones you do track, either through consumption records or year-end physical counts. Replacement belts pulled from a parts room, gallons of industrial solvent counted at year-end, maintenance parts logged against work orders. Once you are tracking consumption, the stricter timing rule applies, whatever the per-item cost.¹

The underlying item still has to qualify as materials and supplies in the first place: tangible property used in your operations that isn’t inventory and that meets at least one of the regulation’s criteria — a repair or maintenance part, a fuel or lubricant expected to be consumed within 12 months, property with a useful life of 12 months or less, property costing $200 or less, or property the IRS has specifically identified. One category is enough. A $3,000 filter that lasts eight months qualifies on useful life; a $150 tool with a five-year life qualifies on cost.

Deducting on Consumption

The core rule is simple to state and easy to get wrong. Deduct in the year first used or consumed. Buying does not equal using. A late-December parts order that sits sealed in a crate produces no deduction for that year.¹

The unused portion sits on the balance sheet as an asset until you draw it down. The deduction itself is claimed as an ordinary and necessary business expense under IRC Section 162.²

Cash-basis taxpayers do not get a pass. Cash-method accounting normally lets you deduct when you pay, but non-incidental supplies are an exception: you still wait for consumption unless you elect the de minimis safe harbor described below. If the IRS challenges a deduction, the burden is on you to show how much was actually used, so consumption documentation matters as much as the purchase invoice.

Deducting Sooner: The De Minimis Safe Harbor

The de minimis safe harbor under Treasury Regulation 1.263(a)-1(f) lets you expense qualifying low-cost items when you pay for them rather than waiting for consumption. It is an annual election, and the per-invoice or per-item ceiling depends on whether your business has an Applicable Financial Statement (AFS):

With an AFS, the threshold is $5,000 per invoice or per item.
Without an AFS, the threshold is $2,500 per invoice or per item.

Most small businesses fall under the $2,500 limit. An AFS generally means an SEC filing, an audited GAAP financial statement used for credit or shareholder reporting, or a statement filed with another federal agency for non-tax purposes.³

How to Elect It

Two things need to be in place. Have a written accounting policy at the start of the tax year stating that you expense items below the applicable threshold for book purposes. Then attach a statement titled “Section 1.263(a)-1(f) de minimis safe harbor election” to your timely filed federal return (including extensions) for the year you paid the amounts. The statement needs your name, address, taxpayer identification number, and a declaration that you are making the election.⁴

The election is all-or-nothing for the year. If you make it, every qualifying expenditure below the ceiling gets expensed; you cannot pick and choose. It resets annually, so you can elect in one year and skip the next.

Rotable and Temporary Spare Parts

Rotable spare parts are components you pull off equipment, repair or refurbish, and reinstall on the same or different equipment. Temporary spare parts are stopgaps used while a permanent part is being fixed. Both follow their own timing rules.

Under the general rule, you treat a rotable or temporary spare part as used or consumed only when you finally dispose of it, not when you first install it. That can push the deduction out for years across multiple install-remove-repair cycles.¹

Optional Method

The regulations offer an optional method that pulls the deduction forward. You deduct the cost when the part is first installed. When you later remove it, you include its fair market value in gross income and add that value plus any removal and repair costs to the part’s basis. When it goes back in service, you deduct the accumulated basis. The cycle repeats until final disposal, when any remaining basis is deducted.

You have to apply the optional method to all rotable and temporary spare parts in the same trade or business. It is a formal method of accounting under Section 446(a), so switching in or out means following the IRS’s change-in-accounting-method procedures.

Election to Capitalize and Depreciate

A third route exists for rotable, temporary, and standby emergency spare parts. You can elect to capitalize the cost and depreciate it instead of applying either consumption rule. You make the election part by part, by capitalizing the cost in the year of payment and starting depreciation when the asset is placed in service, on your timely filed original return. Once capitalized, the part is no longer treated as materials and supplies.

Supplies Versus Inventory

Non-incidental supplies support operations; inventory becomes what you sell. The lubricant in a machine is a supply. The steel that machine forms into a finished product is inventory. Raw materials physically incorporated into a product must be treated as inventory regardless of cost, and inventory costs flow through cost of goods sold under IRC Section 471 rather than being deducted as a business expense.⁵

There is one crossover. Under IRC Section 471(c), a business meeting the gross receipts test in Section 448(c) — average annual gross receipts of $25 million or less over the prior three years, indexed for inflation — can elect to treat its inventory as non-incidental materials and supplies. Costs then get deducted on consumption rather than run through full inventory accounting. The change is treated as initiated by the taxpayer with IRS consent, so no separate permission request is needed.

Records You Need to Support the Deduction

The consumption rule only works if you can prove consumption. That means purchase invoices for what you bought and what you paid, plus something that shows what left the shelf and when: opening and closing physical counts, monthly consumption logs, work orders that reference parts pulled from stock, or a running inventory spreadsheet with quantities on hand and quantities used.

Keep records for at least three years from the date you file the return claiming the deduction, or two years from the date you paid the tax, whichever is later. If you underreport income by more than 25%, the retention window stretches to six years.⁶

If you use the de minimis safe harbor, keep your written accounting policy and a copy of the election statement filed with the return. If you use the optional method for rotable parts, keep records of every installation, removal, repair, and reinstallation, along with the fair market values used at each step. The IRS does not require a particular format, but whatever you use has to be detailed enough to survive a challenge. A shoebox of receipts with no consumption data will not.

1
eCFR. 26 CFR 1.162-3 – Materials and Supplies
2
Office of the Law Revision Counsel. 26 USC 162 – Trade or Business Expenses
3
Internal Revenue Service. IRS Notice 2015-82 – Increase in De Minimis Safe Harbor Limit for Taxpayers Without an Applicable Financial Statement
4
Internal Revenue Service. Tangible Property Final Regulations – Frequently Asked Questions
5
Office of the Law Revision Counsel. 26 USC 471 – General Rule for Inventories
6
Internal Revenue Service. How Long Should I Keep Records?