Inventory Flow Assumptions

Accounting terms for FIFO, first-in first-out, and LIFO inventory flow assumptions.

Inventory Flow Assumptions covers FIFO, first-in first-out, and LIFO inventory flow assumptions.

Use these pages when inventory accounting changes gross margin, working capital, taxable income, obsolescence risk, or cash-conversion analysis. It sits inside Inventory Accounting, so readers can move up when the broader accounting context matters.

Use the table below to choose the narrower accounting branch before applying a term to a statement line, model input, audit trail, tax schedule, covenant test, or management report.

What This Branch Covers

AreaUse it for
FIFOFIFO is an inventory cost-flow assumption that assigns the oldest costs to cost of goods sold and leaves newer costs in ending inventory.
First-in, First-OutInventory cost-flow assumption that treats the earliest purchased goods as sold first, affecting COGS and inventory values.
LIFOLIFO is an inventory cost-flow assumption that assigns the most recent costs to cost of goods sold before older inventory costs.

What to Check

  • Inventory class, cost flow assumption, unit cost, production stage, WIP balance, lower-of-cost-or-market test, and write-down trigger.
  • Purchase record, production report, count sheet, costing system, COGS reconciliation, and note disclosure.
  • Effect on gross profit, working capital, cash conversion, taxes, obsolescence, and valuation multiples.
  • Whether the issue is raw materials, WIP, finished goods, consignment, spare parts, or inventory reserves.
  • Comparability across FIFO, LIFO, weighted average, standard cost, and reporting periods.

Common Mistakes

  • Treating inventory value as guaranteed sale value.
  • Ignoring obsolete, slow-moving, consigned, or written-down inventory.
  • Comparing gross margins without checking cost-flow assumptions.
  • Mixing production cost, period cost, and inventory reserve concepts.

Inventory-accounting content is educational and does not provide accounting, tax, audit, legal, inventory-management, investment, or valuation advice.

In this section

Choose a subsection first. Deeper term pages live inside each subsection, which keeps large topic hubs readable.

FIFO

Learn how first in, first out assigns older inventory costs to cost of goods sold, with a worked example and comparison with LIFO and weighted average.

LIFO

Learn how last in, first out assigns recent inventory costs to cost of goods sold, including layers, LIFO liquidation, reserve analysis, and IFRS differences.

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