How the Choice Between LIFO and FIFO Inventory Valuation Impacts Reported Profit and Taxes During Inflation

Corporate controllers and chief financial officers face a strict binary choice when filing their annual tax returns: they can either maximize their company's reported public earnings, or they can minimize their immediate corporate tax bill. They cannot legally do both. This trade-off is governed by the inventory valuation method they select—specifically, whether they adopt First-In, First-Out (FIFO) or Last-In, First-Out (LIFO) accounting. By filing IRS Form 970, a US-based company can elect to use LIFO, a mechanism that acts as a highly effective, government-subsidized cash flow preservation tool during periods of sustained inflation.[3]

The mechanical difference between the two approaches dictates exactly how a company calculates its Cost of Goods Sold (COGS) for a given fiscal year. Under the FIFO method, the oldest inventory costs are matched against current revenue. If a hardware retailer bought 1,000 power drills at $10 each in January 2025 and another 1,000 identical drills at $20 each in June 2025, a holiday sale of 1,500 drills in December would trigger a COGS of $20,000 under FIFO. The remaining 500 drills sitting on the balance sheet would be valued at the newer $20 price, accurately reflecting the current market reality of what it costs to replace that inventory.

LIFO completely flips that cost-flow assumption. Under LIFO, the most recently acquired items are assumed to be sold first, regardless of which physical box is actually pulled off the warehouse shelf. Using the exact same 1,500 drill sale, the retailer would expense the 1,000 newer drills at $20 each, plus 500 of the older drills at $10 each, generating a total COGS of $25,000. This $5,000 increase in COGS directly reduces the company's taxable income, lowering its immediate tax liability. "By reducing the time between when a unit of inventory is acquired and when its costs are deducted, LIFO prevents inflation from reducing the real value of deductions for costs of goods sold," according to the Tax Foundation.[4]

The cumulative difference between a company's inventory value under FIFO and its reported value under LIFO is formally known as the "LIFO reserve." During periods of sustained inflation, this reserve grows continuously as the gap between historical costs and current replacement costs widens. For massive retailers, heavy equipment manufacturers, and pharmaceutical distributors, the LIFO reserve can defer billions of dollars in taxable income over decades. Because the tax is deferred until the inventory is eventually liquidated, this mechanism effectively functions as an interest-free loan from the federal government, providing critical liquidity that can be reinvested into core operations.

However, the Internal Revenue Service extracts a heavy public relations price for this tax deferral through a strict mandate known as the LIFO conformity rule, codified in Section 472(c) of the Internal Revenue Code. "Under the LIFO conformity rule in Sec. 472(c), if LIFO is used on a taxpayer's tax return, no other method can be used to value inventory to calculate income, profit, or loss in any report or statement covering the same tax year," states the Journal of Accountancy. The government forces companies to prove their commitment to the lower valuation.[5]

"The LIFO Conformity Rule was introduced to prevent businesses from manipulating inventory valuation to gain tax advantages while presenting higher profits in their financial statements," according to Source Advisors. Because of this uncompromising mandate, a company that slashes its tax bill using LIFO must also report that artificially depressed net income to its shareholders, its lenders, and the Securities and Exchange Commission (SEC). The corporate controller must intentionally accept weaker earnings per share (EPS) and a potentially depressed stock price in order to secure the underlying cash flow advantage.[1]

This domestic tax strategy collides violently with global accounting standards, creating a massive headache for multinational corporations. While the US Generally Accepted Accounting Principles (GAAP) permit both valuation methods, the International Financial Reporting Standards (IFRS)—which govern accounting in more than 120 countries—explicitly ban LIFO. "First-in, first-out (FIFO) and weighted-average cost are acceptable accounting methods for determining cost of inventory. Last-in, first-out (LIFO) is not permitted," notes Deloitte regarding IFRS standards. Standard setters argue that LIFO leaves outdated, artificially low inventory values on the balance sheet, misleading investors about a company's true asset value.[2]

This international prohibition forces US-based multinational corporations into complex compliance maneuvers. A US parent company might use LIFO domestically to shield its profits from the IRS, but its European and Asian subsidiaries must use FIFO to comply with local IFRS mandates. If a company decides to abandon LIFO entirely to streamline its global accounting infrastructure, it triggers a massive, immediate tax event: the entire accumulated LIFO reserve becomes taxable income, typically recognized through a Section 481(a) adjustment that is spread over four years to prevent immediate insolvency.[3]

The macroeconomic environment and the company's capital structure dictate the final decision. In a deflationary environment, the math reverses, and LIFO actually increases taxable income because the newer, cheaper goods are expensed first. But during inflationary spikes—such as the global supply chain shocks of 2022 through 2025—the tax deferral benefits of LIFO often vastly outweigh the penalty of lower reported earnings. The board of directors must weigh the optics of a strong public income statement against the tangible utility of retained cash, knowing that a reversal later will trigger a massive, immediate tax liability.