A finance and accounting concept defining a method, measure, or process used to record activity and support financial decisions. It specifies how value, risk, or performance is measured or controlled through standardized rules and routines. It does not ensure correctness without reliable inputs, appropriate assumptions, and effective review and controls. It materially affects decisions and compliance by shaping how organizations allocate capital, report results, and manage exposure. The concept is generally stable, though standards, regulation, and tools evolve over time.

Principle

Assign costs to cost of goods sold and ending inventory based on chronological cost layers: consume earliest layers first unless a different, consistent method is justified and disclosed.

Demonstration

A retailer buys 100 units at $10 and later 100 units at $12. If 120 units are sold under FIFO, COGS = (100 × $10) + (20 × $12) = $1,240 and ending inventory = (80 × $12) = $960.

Misapplication

Using FIFO language but actually applying sporadic or inconsistent layer consumption in records, or failing to disclose the method and its impact on margins and taxes.

Consequence

In periods of rising prices, FIFO produces lower cost of goods sold and higher reported profit and ending inventory values compared with methods that charge newer costs to COGS.

Reversal

LIFO assumption, where the most recently acquired costs are charged to cost of goods sold first, producing the opposite effect on profit and inventory valuation during inflationary periods.

Boundary

A cost-flow assumption that can be applied under many accounting frameworks; it is a valuation convention and need not match physical outflow but must be applied consistently and disclosed.

Semantic Tension

Tension exists between FIFO as an accounting convention and the actual physical flow of goods; for some businesses FIFO matches physical flow (perishables), for others it is purely a measurement choice.

Synthesis

FIFO treats oldest cost layers as sold first, affecting COGS and inventory carrying values; it is simple to apply, tends to increase profit during inflation, and must be applied consistently and disclosed.