What Is LIFO in Accounting: Tax Effect, Reserve, and Liquidation

LIFO in accounting, short for last-in, first-out, is an inventory costing method that assigns the price of the most recently purchased goods to each sale and leaves the oldest purchase costs sitting on the balance sheet as remaining inventory. When prices are rising, that pattern pushes higher costs through the income statement, lowers reported profit, and reduces the current tax bill. U.S. tax law permits LIFO, but it comes with strings attached: a company that uses it for taxes must also use it in the financial statements it gives shareholders and creditors.¹

How LIFO Assigns Costs

LIFO stacks inventory purchases into chronological cost layers. Each new purchase at a new price adds a fresh layer on top. When a sale is recorded, the accountant pulls the cost from the top of the stack, meaning the most recent purchase price becomes the cost of that sale. Older layers stay put at the bottom until every newer layer above them has been sold through.

Physical movement of goods does not have to match this pattern. A warehouse can still ship whichever box is closest to the door. LIFO governs how dollars move through the ledger, not how product moves through the building. It is a cost-flow assumption, nothing more.

LIFO Compared With FIFO and Weighted Average

Three costing methods dominate U.S. accounting, and a small example shows how they diverge. Say a company makes three purchases: 100 units at $8, 150 units at $10, and 200 units at $12. It then sells 300 units.

Under FIFO (first-in, first-out), the oldest costs are used first. The sale draws all 100 units at $8, all 150 at $10, and 50 at $12, for a cost of goods sold of $2,900.
Under LIFO, the newest costs are used first. The sale draws all 200 units at $12 and 100 at $10, for a cost of goods sold of $3,400.
Under weighted average, all purchases blend into a single per-unit price. Total cost of $4,700 across 450 units gives roughly $10.44 per unit, so 300 units cost about $3,133.

On identical sales, LIFO reports $500 more in expense than FIFO. That gap flows straight through to taxable income, which is why the choice of method matters far more than a routine bookkeeping decision.

Why Companies Choose LIFO: The Tax Effect

Because LIFO assigns the most recent, typically most expensive, purchase costs to each sale, it produces a higher cost of goods sold than FIFO during inflationary periods. Higher expenses mean lower gross profit, lower taxable income, and a smaller tax bill. For businesses dealing in commodities, raw materials, or any goods whose prices climb over time, the resulting tax deferral can be substantial, and that is the main reason companies elect LIFO in the first place.

The trade-off is reported earnings. A LIFO company shows lower net income than an otherwise identical FIFO company that sold the same goods at the same prices. An investor comparing two firms in the same industry without adjusting for inventory method can draw the wrong conclusion about which one is more profitable.

What LIFO Does to the Balance Sheet

Because the newest costs flow out to cost of goods sold, the oldest cost layers stay behind as ending inventory. A company that has been on LIFO for decades may carry inventory on its books at prices from a much earlier economic era, sitting far below what it would cost to replace those goods today.

One consequence is tax-specific: LIFO users cannot apply the lower-of-cost-or-market rule to write inventory down for tax purposes.¹ A company that used lower-of-cost-or-market before adopting LIFO must first adjust inventory back to cost. The reasoning is that LIFO already produces a conservative income figure, and stacking a write-down on top would let taxpayers double up on deductions.

The LIFO Reserve

To bridge the gap between the aged costs on a LIFO balance sheet and current prices, U.S. financial reporting requires LIFO companies to disclose the LIFO reserve in their footnotes. The reserve is the dollar difference between the company’s LIFO inventory value and what the same inventory would be worth under FIFO or at replacement cost. This disclosure, grounded in SEC Staff Accounting Bulletin No. 58, lets an analyst put a LIFO company and a FIFO competitor on comparable footing.

The reserve also carries information. A growing LIFO reserve signals that current prices are pulling well above the historical costs on the books. A shrinking reserve can point to falling prices or to a LIFO liquidation. Analysts routinely add the reserve back to inventory and adjust cost of goods sold downward to approximate what the financials would look like under FIFO.

Dollar-Value LIFO

Most companies on LIFO do not track individual items through separate cost layers. They use dollar-value LIFO, which groups inventory into broad pools and measures changes using price indexes rather than unit counts.² Each pool has a base-year cost, and at period end the company calculates a cumulative price index to see whether the pool grew or shrank in real terms.

For a retailer carrying thousands of SKUs, item-by-item LIFO layers would be unworkable. Dollar-value LIFO lets the retailer treat a whole product category as one pool, strip out price inflation, and add a new LIFO layer only when quantities actually increase. The IRS accepts this approach as long as the pools and indexes are reasonable and consistently applied.

The IRS Conformity Rule

Under IRC Section 472, any business that uses LIFO to compute taxable income must also use LIFO as its primary inventory method in the financial statements it provides to shareholders, partners, and creditors.¹ This is the LIFO conformity rule. It keeps companies from using one method to shrink the tax bill while using another to inflate reported profits.

Electing LIFO requires filing IRS Form 970 with the tax return for the first year of use.³ Once filed, the election is irrevocable unless the IRS grants permission to change.⁴ If the IRS finds a conformity violation, such as an annual report showing FIFO figures on the face of the income statement, it can disqualify the LIFO election altogether and force the company to recompute prior years’ income at higher valuations, with back taxes and interest to follow.¹

What Supplemental Disclosures Are Allowed

The rule is strict but not absolute. A LIFO company may still present non-LIFO figures as supplemental or explanatory information, as long as those figures do not appear on the face of the income statement.⁵ Permitted disclosures include footnotes showing what income would be under FIFO, management discussion sections of annual reports, news releases, and letters to creditors. That exception is what lets companies publish the LIFO reserve in their footnotes without putting the election at risk.

LIFO Under U.S. GAAP and IFRS

U.S. Generally Accepted Accounting Principles, codified in ASC Topic 330, allow LIFO alongside FIFO and weighted average. The flexibility ties back to the conformity rule: allowing LIFO for tax purposes without also allowing it for financial reporting would be impractical.

International Financial Reporting Standards take the opposite position. IAS 2, the inventory standard, prohibits LIFO outright. Most countries outside the United States follow IFRS, so a multinational with U.S. operations on LIFO and foreign subsidiaries on IFRS has to maintain separate inventory records or convert figures at consolidation. The divergence remains one of the most frequently cited obstacles to convergence between the two frameworks.

LIFO Liquidation

A LIFO liquidation happens when a company sells more inventory than it buys during a period, forcing the accounting system to dip into older, cheaper cost layers. Those layers may carry costs from years or even decades ago, so cost of goods sold drops sharply and reported profits spike, even though the underlying economics have not improved. This is where LIFO can produce genuinely misleading financial statements.

The profit surge is real for tax purposes too, which means a bigger tax bill in the liquidation year. For involuntary liquidations caused by supply disruptions such as trade embargoes or government-mandated production cuts, IRC Section 473 offers limited relief: the company can elect to defer the income effect if it replaces the liquidated inventory within a designated replacement period.⁶ Voluntary liquidations get no such relief. The SEC requires companies to disclose the income effect of material liquidations, and analysts watch those disclosures closely because the profits are essentially one-time windfalls.

Switching Away From LIFO

Leaving LIFO is neither quick nor cheap. A company that wants to move to FIFO or weighted average files IRS Form 3115, Application for Change in Accounting Method, with its tax return for the year of the change.⁷ The IRS treats the change as an automatic change under Designated Change Number 56, which removes the need for advance approval but requires precise filing procedures, including a signed copy sent to the IRS National Office.

The real cost is the Section 481(a) adjustment. When a company moves from LIFO to FIFO, the entire LIFO reserve, meaning all the deferred income accumulated across every year the company used LIFO, becomes taxable.⁸ For a positive adjustment, which a LIFO-to-FIFO switch almost always produces, current IRS procedures generally allow the additional income to be spread over four taxable years. A company with a $40 million LIFO reserve would add $10 million to taxable income in each of four consecutive years. That softens the impact without eliminating it.

LIFO Recapture When Converting to an S Corporation

A sharper version of the same problem hits C corporations that elect S corporation status while still on LIFO. Under IRC Section 1363(d), the entire LIFO recapture amount, the difference between the FIFO value and the LIFO value of inventory, must be included in gross income for the corporation’s final C corporation tax year.⁹ The resulting tax is payable in four equal annual installments, starting with the return for that final C corporation year and continuing over the next three years. No interest accrues during the installment period, but the recapture itself is mandatory and cannot be sidestepped by changing inventory methods before the S election takes effect. Any company weighing a C-to-S conversion with significant LIFO reserves should model this tax hit before filing the election.

1
Office of the Law Revision Counsel. 26 USC 472 – Last-in, First-out Inventories
2
eCFR. 26 CFR 1.472-2 – Requirements Incident to Adoption and Use of LIFO Inventory Method
3
Internal Revenue Service. About Form 970, Application to Use LIFO Inventory Method
4
Internal Revenue Service. Form 970 Application to Use LIFO Inventory Method
5
Internal Revenue Service. Practice Unit – LIFO Conformity
6
Office of the Law Revision Counsel. 26 USC 473 – Qualified Liquidations of LIFO Inventories
7
Internal Revenue Service. Instructions for Form 3115 Application for Change in Accounting Method
8
Office of the Law Revision Counsel. 26 USC 481 – Adjustments Required by Changes in Method of Accounting
9
Office of the Law Revision Counsel. 26 USC 1363 – Effect of Election on Corporation