What Is FIFO Inventory Accounting? (GAAP Standards & Specs)

FIFO, or first-in, first-out, is an inventory cost method that assigns the earliest eligible inventory costs to cost of goods sold first. The newest costs remain in ending inventory. Under U.S. GAAP, FIFO is allowed when applied consistently, but inventory must also meet applicable measurement rules, including the lower-of-cost-and-net-realizable-value test.

As prices and supply costs change, the method a business uses can affect its reported inventory, cost of goods sold, and profit. That does not mean the business changes what it physically sells. FIFO is an accounting rule for assigning costs, not a warehouse instruction.

I approach a FIFO calculation as a short sequence: identify eligible costs, sort them by date, assign the oldest costs to sales, then check the remaining inventory’s value. The example below shows each step and where GAAP requirements matter.

FIFO Inventory Accounting: Purpose, GAAP Framework, and Cost-Flow Assumption

FIFO is one way to assign inventory costs between goods sold and goods still on hand. U.S. GAAP addresses inventory in FASB Accounting Standards Codification (ASC) 330. FIFO is an acceptable method when it is applied consistently to similar inventory in similar circumstances.

The phrase “first in, first out” can sound like a rule about which physical item must leave a store or warehouse first. It is not. FIFO assumes that the earliest costs are assigned to sales first, whether or not workers actually ship or use those specific units first.

For example, a retailer may sell a newly received item while an older item remains on the shelf. Its physical handling can differ from its accounting cost flow. Some businesses do rotate physical goods by age, such as to manage expiration dates, but that practice is separate from the FIFO cost assumption.

Under FIFO:

• The earliest eligible inventory costs go to cost of goods sold (COGS).
• The newest eligible costs usually remain in ending inventory.
• The business applies its chosen method consistently to comparable inventory and circumstances.
• The business also follows the applicable GAAP rules for what costs enter inventory and how inventory is measured.

ASC 330 is the key U.S. GAAP reference for inventory accounting. The details can depend on the nature of the inventory and the facts of the business, so a company should document its policy and review the guidance that applies to its situation. FIFO is not automatically the best method for every business.

Key takeaway: FIFO describes cost assignment. It does not guarantee that the oldest physical goods are sold first, and it does not replace GAAP’s measurement rules.

FIFO Calculations, Cost Layers, and Inventory Valuation Requirements

A cost layer is a group of inventory units recorded at the same unit cost from a dated purchase or production event. FIFO uses those layers in date order to assign COGS and calculate ending inventory. After the calculation, the business must assess whether the inventory’s recorded cost exceeds its net realizable value.

How to calculate FIFO COGS and ending inventory

To build a FIFO schedule, first establish the cost pool. Identify the inventory units and the eligible costs of acquiring or producing them. Costs that applicable GAAP requires the business to expense should not be added to inventory. The exact cost categories depend on the facts and relevant accounting guidance.

Next, list the cost layers by date, quantity, and unit cost. Assign the earliest costs to the units sold. The cost of the units left over becomes the FIFO cost of ending inventory.

Consider this illustrative example:

The business assigns the first 100 units sold to the $10 layer, then assigns the next 20 units sold to the $12 layer.

• COGS: (100 × $10) + (20 × $12) = $1,240
• Ending inventory: 80 units × $12 = $960

The units in the example are assumed to be comparable. Real schedules may include more layers, returns, freight or production costs, and other details that require review.

Lower of cost and net realizable value

FIFO cost is not always the final amount reported for inventory. Under ASC 330, inventory measured using FIFO is generally reported at the lower of cost and net realizable value (NRV).

NRV is the estimated ordinary-course selling price minus reasonably predictable costs of completion, disposal, and transportation. It is an estimate, not simply the expected selling price.

In the example, suppose the NRV of each of the 80 remaining units is $11. Their total NRV is $880, compared with FIFO cost of $960. If those assumptions are supported and the lower-of-cost-and-NRV rule applies, the inventory would be written down by $80, from $960 to $880.

A business should support its NRV estimate with relevant facts and apply the accounting guidance that fits its inventory. It should also record and explain material judgments as required by applicable GAAP.

Key takeaway: Calculate FIFO cost by layers, then perform the required valuation test. Do not stop at the cost schedule.

Applying FIFO in Periodic and Perpetual Systems: Controls and Common Errors

A periodic system updates inventory and COGS at set intervals, often at the end of an accounting period. A perpetual system updates records as transactions occur. Both can use FIFO, but their timing and recordkeeping differ. With the same transactions and no complications, periodic and perpetual FIFO produce the same ending inventory and COGS.

In a periodic system, the business totals units available for sale and units sold for the period. It assigns the earliest costs to the total units sold, then assigns the remaining layers to ending inventory.

In a perpetual system, the business updates its cost layers whenever inventory is received or sold. At each sale, it assigns the earliest available layer costs to COGS. This can provide more current records, but it relies on accurate, timely transaction data.

For example, using the table above, if the 120-unit sale occurs after both inventory layers are available, either system assigns $1,240 to COGS and leaves 80 units at $12 each. If transactions occur in a different order, the schedule must reflect when each purchase and sale occurred. Do not assume that a calculation is correct just because the final total looks plausible.

Practical controls include:

• Match purchase and production records to dated inventory layers.
• Record sales, returns, and receipts in the correct period.
• Reconcile inventory records to the general ledger and physical counts.
• Investigate quantity or cost differences before finalizing statements.
• Keep support for cost inputs, NRV estimates, and policy choices.

Common mistakes include treating FIFO as a physical shipping rule, using the newest costs for COGS, omitting an eligible cost layer, or skipping the NRV test. A related error is changing methods without assessing the consistency and disclosure requirements that apply.

Key takeaway: Periodic and perpetual FIFO can reach the same result, but only when the records capture the same transactions and cost layers accurately.

Financial-Statement, Tax, and Decision-Making Effects of FIFO

FIFO affects how inventory costs appear in financial statements. Its impact depends on the actual cost pattern, the amount and timing of purchases and sales, and the inventory left at period-end. It does not always raise profit or inventory value, so comparisons should use the business’s real cost layers.

When purchase costs rise, FIFO commonly assigns older, lower costs to COGS and leaves newer, higher costs in ending inventory. Compared with LIFO under the same rising-cost assumptions, this often means lower COGS and higher gross profit. When costs fall, the direction may differ. These are common effects, not guaranteed results.

Using the earlier example, FIFO COGS is $1,240. If the same 120 units were assigned using LIFO, and both layers were available before the sale, COGS would be $1,440: 100 units at $12 and 20 at $10. The $200 difference would also affect gross profit, assuming revenue and other costs stay the same. LIFO is not permitted under IFRS, while IAS 2 permits FIFO and weighted average for interchangeable inventory. U.S. GAAP and IFRS should not be treated as identical.

A company’s financial reporting method does not, by itself, establish its tax treatment. Tax results depend on the rules that apply to the taxpayer and the method used for tax reporting. A business should check with a qualified tax professional before using a financial-statement calculation to estimate a tax bill.

For planning, FIFO can help readers understand the cost attached to remaining inventory. But reported profit under one method is not, by itself, a measure of cash available or business performance. Consider the method, price changes, inventory levels, and disclosures together.

Key takeaway: FIFO can change reported COGS and inventory as costs move, but the size and direction of the effect depend on the facts.

FIFO Inventory Accounting: Final Review and FAQs

A sound FIFO process links the cost schedule to the inventory records, general ledger, and valuation review. Before reporting, confirm the method, quantities, dates, eligible costs, and NRV assessment. Then document material judgments and provide the inventory policy and other disclosures required by applicable U.S. GAAP.

What does FIFO mean in inventory accounting?

FIFO means first-in, first-out. It assigns the earliest inventory costs to COGS first and generally leaves the newest costs in ending inventory. It is a cost-flow assumption, not a requirement about which physical goods must be sold first.

Is FIFO allowed under U.S. GAAP?

Yes. FIFO is an acceptable inventory-costing method under U.S. GAAP. A business should apply its method consistently to similar inventory and circumstances and follow the other inventory requirements in ASC 330.

Does FIFO require a business to sell its oldest goods first?

No. FIFO does not require the oldest physical goods to be shipped or used first. It describes how the business assigns inventory costs in its accounting records.

How do you calculate FIFO COGS?

List inventory cost layers by date, then assign the earliest eligible costs to the units sold. Add those costs to calculate COGS. The costs attached to the units left over form FIFO ending inventory, before any required valuation adjustment.

How does FIFO value ending inventory?

FIFO generally leaves the newest cost layers in ending inventory. For FIFO inventory under U.S. GAAP, the business generally reports the lower of cost and NRV, so the recorded amount may be less than FIFO cost.

Do periodic and perpetual FIFO give the same result?

They do when they use the same transactions and there are no complications that change the calculation. Periodic FIFO assigns costs at the end of the period. Perpetual FIFO updates layers as purchases and sales occur.

Does FIFO always increase profit when costs rise?

No. With rising costs, FIFO commonly produces lower COGS and higher gross profit than LIFO, all else equal. But the result depends on the actual cost layers, purchases, sales, and remaining inventory.

Is FIFO permitted under IFRS?

Yes. IAS 2 permits FIFO for interchangeable inventory, as well as weighted average. IAS 2 prohibits LIFO, so U.S. GAAP and IFRS do not permit all the same inventory cost methods.

What records support a FIFO calculation?

Keep dated purchase or production records, quantities, unit costs, sales and return records, and inventory count support. Also retain documentation for cost inputs, NRV estimates, reconciliations, and relevant accounting-policy disclosures.

(This article was written by one of our staff writers, Nathan Sterling. Visit our Meet the Team page.)