LIFO and FIFO Change Reported Profit Without Changing Anything Real
Two companies with identical inventory and identical sales can report different profits purely from the order in which they assume goods left the shelf. In inflationary periods the gap is large.
The Question Being Answered
A company buys inventory at different prices over time. When it sells a unit, which cost does it record?
The physical answer is often unknowable and usually irrelevant. Identical units are interchangeable, and nobody tracks which specific barrel of oil or box of screws left the warehouse. So accounting standards permit assumptions, and the assumption chosen changes reported results.
The Two Main Methods
First in first out assumes the oldest inventory is sold first. In a period of rising prices, that means cost of goods sold reflects older, cheaper purchases, so reported profit is higher and the inventory remaining on the balance sheet is valued at recent, higher prices.
Last in first out assumes the newest inventory is sold first. Cost of goods sold reflects recent, expensive purchases, so reported profit is lower, and the inventory remaining on the balance sheet is carried at old, potentially very stale costs.
Same warehouse, same sales, same cash. Different reported profit, entirely because of an assumption about which unit left first.
Why a Company Would Choose Lower Profit
Choosing to report lower profit sounds irrational until taxes enter. In the United States, a company using LIFO for tax purposes must also use it for financial reporting, a requirement known as the LIFO conformity rule.
During inflation, LIFO produces higher cost of goods sold, lower taxable income, and therefore lower cash taxes. The company accepts a worse looking income statement in exchange for keeping cash. That is a real economic benefit obtained by accepting a cosmetic cost, which is generally a good trade.
This is also why LIFO is largely a United States phenomenon. International financial reporting standards prohibit it, so companies reporting under IFRS use FIFO or weighted average cost.
The Balance Sheet Distortion
The consequence people forget sits on the balance sheet. Under LIFO, the inventory remaining is assumed to be the oldest, so it is carried at costs that may be decades out of date.
A company using LIFO for many years can carry inventory at a fraction of its replacement cost. Companies disclose the difference as the LIFO reserve, which is the amount that would be added to inventory if FIFO had been used. Adding that reserve back is required before comparing a LIFO company's balance sheet to a FIFO company's.
LIFO Liquidation
A specific trap deserves attention. If a LIFO company reduces its inventory quantity, it begins selling those old, cheap layers. Cost of goods sold drops sharply and profit surges.
That profit increase looks operational and is not. It is the release of decades of deferred cost, and it happens exactly when a company is shrinking, which is when results would otherwise look worst. Companies disclose LIFO liquidation effects, and finding an earnings improvement driven by it is a genuine red flag rather than good news.
What to Do as an Analyst
Check the inventory accounting policy note before comparing gross margins between companies. If methods differ, adjust using the LIFO reserve to put both on a comparable basis.
Also watch for method changes, which are permitted but must be disclosed and justified. A company switching methods in a period of unusual pressure is worth a closer look.
The Bottom Line
Inventory method changes reported profit, taxes, and balance sheet values without changing a single physical unit. Read the policy note before you compare anything, and treat a LIFO liquidation gain as an accounting release rather than performance.