What Is IRC 471? The General Rule for Inventories

Internal Revenue Code Section 471 is the general rule for inventories: if your business produces, buys, or sells merchandise as a meaningful part of how it earns income, you have to keep inventories at the start and end of each tax year and value them using a method that matches good accounting practice in your industry and clearly reflects income.¹ The practical consequence is that you cannot deduct the cost of goods until the year you actually sell them. For 2026, businesses with average annual gross receipts of $32 million or less over the prior three years can skip most of these rules entirely and use simplified methods instead.²

Who Has to Keep Inventories

The trigger is whether merchandise is an income-producing factor in your business.³ Manufacturers, wholesalers, and retailers clearly qualify. A consulting firm that occasionally passes through a few software licenses probably does not. The line between them is a facts-and-circumstances call, but the IRS draws it broadly, so most businesses handling tangible goods land on the inventory side.

Once you fall inside the rule, you are effectively pushed onto the accrual method for purchases and sales, because measuring income through inventory means matching costs to the period when goods are sold rather than when cash moves.

The Small Business Exemption Under Section 471(c)

Section 471(c) is the escape hatch. If your average annual gross receipts over the prior three tax years do not exceed the inflation-adjusted threshold ($32 million for 2026), you are exempt from the general inventory rules.¹² Tax shelters are excluded from this exemption regardless of size.⁴

A qualifying business gets two choices. The first is the non-incidental materials and supplies method, which treats inventory like supplies and deducts cost when items are used or sold, without formal unit-by-unit tracking. The second is the financial statement conformity method: you use whatever inventory method appears on your applicable financial statement (such as an audited GAAP statement), or if you don’t have one, whatever method your books and records reflect.¹

For sole proprietors and other non-corporate, non-partnership taxpayers, the gross receipts test is applied as though each trade or business were a separate entity. Switching to a simplified method after previously using full inventory accounting counts as a voluntary accounting method change and requires a Section 481(a) adjustment to keep income from being counted twice or slipping through.

Valuing Inventory: Cost or Lower of Cost or Market

For businesses subject to the full rules, Section 471 allows two valuation methods: cost, or the lower of cost or market (LCM).⁵

The cost method is simpler. You carry each item at whatever you paid to acquire or produce it, and that value holds until the item is sold. If market prices drop, you don’t recognize the decline until you sell.

LCM lets you write inventory down when its replacement cost falls below what you originally paid. The comparison is made item by item, not across the inventory as a whole.⁶ “Market” means the current bid price for the basic cost elements in your inventory (direct materials, direct labor, and required indirect costs): for manufacturers, the current cost to reproduce the goods; for resellers, the current wholesale replacement price in the quantities you normally buy. Goods covered by a firm, non-cancelable sales contract at a fixed price must be valued at cost, because there is no real market exposure on those units.

What Counts as “Cost”

The cost you assign is not just the invoice figure. For purchased goods, cost is the invoice price reduced by trade discounts, plus transportation and other charges incurred in acquisition. Strict cash discounts (those approximating a fair interest rate) may be included or excluded, provided you are consistent from year to year.⁷

For goods you produce, cost has three layers: raw materials and supplies that go into the product, direct labor to make it, and an appropriate share of indirect production costs. Selling expenses and any imputed return on capital cannot be treated as indirect production costs.⁷

Manufacturers face more detail. Direct labor covers basic pay, overtime, vacation and holiday pay, sick leave, shift differentials, and payroll taxes for workers directly involved in production. Indirect costs that must be capitalized include facility rent and utilities, repair and maintenance, indirect labor and supervision, indirect materials and supplies, non-capitalized tools, and quality control. Property taxes on production facilities, depreciation on manufacturing equipment, and employee benefits may also have to be capitalized depending on how they are treated in financial reports.⁸ The rule is that costs incident to and necessary for production get absorbed into inventory and reach the income statement only when the finished goods sell.

Retail Inventory Method

Retailers stocking thousands of items at varying markups can use the retail inventory method, which converts the retail selling price of ending inventory back into an approximation of cost through a computed cost complement ratio.⁹ Depending on how markdowns are handled, the result approximates either cost or LCM.

Cost Flow Methods: FIFO, LIFO, and Average Cost

When identical goods have been purchased at different prices over time, a cost flow method decides which purchase price gets matched against revenue. The choice moves taxable income, especially when costs are changing.

FIFO (first in, first out) assumes the oldest inventory sells first. During inflation, FIFO produces higher taxable income because cheaper earlier goods are matched to current revenue, and ending inventory sits at more recent, higher costs.

LIFO (last in, first out) assumes the most recent inventory sells first. When prices are rising, LIFO matches higher-cost goods against revenue and lowers taxable income. It comes with a conformity requirement: if you use LIFO for tax, you must also use it in reports to shareholders, creditors, and other outside parties.¹⁰ You cannot present investors a FIFO income number while giving the IRS a lower LIFO figure. LIFO also must be valued at cost only; it cannot be combined with LCM. Once elected, you continue using LIFO in later years unless the IRS approves a change.

Average cost pools all units and assigns each the weighted average purchase price. It fits fungible goods stored together (chemicals, fasteners, petroleum products) and typically produces income between FIFO and LIFO.

How Section 263A (UNICAP) Sits on Top of Section 471

Section 471 sets the baseline for what goes into inventory. Section 263A adds a layer. UNICAP requires taxpayers to capitalize additional purchasing, handling, storage, and mixed service costs that Section 471 alone might have left as deductible period expenses.¹¹

UNICAP applies to tangible personal property you produce and to property you acquire for resale. If your business does both, both categories apply.

The exemption threshold mirrors Section 471(c): average annual gross receipts of $32 million or less over the prior three years (the 2026 figure) means Section 263A does not apply.¹¹² Both exemptions use the same Section 448(c) gross receipts test, so crossing the $32 million line triggers both rule sets at once. For businesses above the threshold, failing to capitalize the additional costs UNICAP requires is one of the more common and expensive inventory errors picked up on audit.

Consistency and Changing Methods

Whatever method you adopt, you must apply it consistently year after year. Without that requirement, a business could toggle between cost and LCM, or between FIFO and LIFO, whenever the switch happened to lower its tax bill. The IRS treats that kind of movement as a failure to clearly reflect income.

Legitimate changes require IRS consent, filed on Form 3115.¹² Many inventory changes qualify for automatic consent, meaning you file and comply with published requirements without waiting for an individual ruling. Changes outside automatic consent need a formal request and approval before the switch.

Every method change triggers a Section 481(a) adjustment, which captures the cumulative difference between the old method and the new one so income is not double-counted or missed during the transition.¹³ A positive adjustment (one that increases income) generally can be spread over four tax years. A negative adjustment is typically taken in full in the year of change. The spread matters in practice: a business that has been undervaluing inventory for years can face a large positive 481(a) adjustment, and the four-year window keeps it from landing as a single tax bill.

Penalties for Inventory Errors

Getting inventory wrong does not stop at a corrected return. When improper inventory valuation causes a substantial understatement of income tax, the IRS can add a 20% accuracy-related penalty on the underpaid portion.¹⁴ A gross valuation misstatement doubles that to 40%.

A substantial valuation misstatement exists when the claimed value of property is 150% or more of the correct amount, and the penalty applies only if the resulting underpayment exceeds $5,000 ($10,000 for C corporations).¹⁴ Common audit triggers include personal consumption of inventory that is never added back to income, inconsistent use of the retail inventory method, and improperly excluding required indirect costs from capitalization. The penalty does not apply if you can show reasonable cause and good faith, but “I didn’t know the rules” rarely clears that bar on its own.

1
Office of the Law Revision Counsel. 26 USC 471 – General Rule for Inventories
2
Internal Revenue Service. Rev. Proc. 2025-32
3
eCFR. 26 CFR 1.471-1 – Need for Inventories
4
Office of the Law Revision Counsel. 26 USC 448 – Limitation on Use of Cash Method of Accounting
5
Internal Revenue Service. Lower of Cost or Market (LCM)
6
eCFR. 26 CFR 1.471-4 – Inventories at Cost or Market, Whichever Is Lower
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eCFR. 26 CFR 1.471-3 – Inventories at Cost
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eCFR. 26 CFR 1.471-11 – Inventories of Manufacturers
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eCFR. 26 CFR 1.471-8 – Inventories of Retail Merchants
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Office of the Law Revision Counsel. 26 USC 472 – Last-in, First-out Inventories
11
Office of the Law Revision Counsel. 26 USC 263A – Capitalization and Inclusion in Inventory Costs of Certain Expenses
12
Internal Revenue Service. About Form 3115, Application for Change in Accounting Method
13
Office of the Law Revision Counsel. 26 USC 481 – Adjustments Required by Changes in Method of Accounting
14
Office of the Law Revision Counsel. 26 USC 6662 – Imposition of Accuracy-Related Penalty