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FIFO Accounting Method Explained For Inventory Costs

A simple cost flow can reshape your books and margins.

Medha Deb
PUBLISHED AUG 12, 2026
8 MIN READ

Understanding FIFO: First-In, First-Out Accounting Method

The FIFO method, which stands for “First-In, First-Out,” is one of the most widely used inventory costing methods in accounting and inventory management. FIFO is a costing approach that assumes the first goods purchased are the first goods sold or disposed of. This method is used to value inventory and calculate the Cost of Goods Sold (COGS), which directly impacts a company’s financial statements and tax obligations.

Both Generally Accepted Accounting Principles (GAAP) and International Financial Reporting Standards (IFRS) accept the FIFO method, making it a universally recognized and trusted accounting practice. Understanding how FIFO works and when to implement it is essential for businesses looking to maintain accurate financial records and optimize their inventory management processes.

How the FIFO Method Works

The FIFO method operates on a straightforward principle: the oldest items in your inventory are assumed to be sold first. When calculating the Cost of Goods Sold under FIFO, you use the cost of your oldest inventory multiplied by the total amount sold. This creates a cost flow that mirrors the natural physical movement of most goods through a business.

For example, if a retailer purchases 100 units of a product at $10 per unit in January and then purchases 100 more units at $12 per unit in March, and the company sells 120 units in April, under the FIFO method, the COGS would be calculated using 100 units at $10 and 20 units at $12, resulting in a total COGS of $1,240.

FIFO is generally the most common approach to inventory accounting because most businesses naturally offload oldest products first anyway. Older inventory might become obsolete and lose value over time, so FIFO simply follows that natural flow of inventory, meaning less chance of mistakes when it comes to bookkeeping.

Key Advantages of Using FIFO

The FIFO method offers several significant advantages that make it the preferred choice for many businesses:

Disadvantages and Limitations of FIFO

While FIFO is widely used, it does have some limitations that businesses should consider:

FIFO vs. LIFO: A Comparative Analysis

Understanding how FIFO differs from LIFO (Last-In, First-Out) is crucial for making informed accounting decisions. While FIFO assumes the oldest inventory is sold first, LIFO assumes the most recent inventory is sold first. This fundamental difference creates significant implications for financial reporting and taxation.

Feature FIFO LIFO
Inventory Flow Assumption Oldest inventory sold first Newest inventory sold first
COGS Calculation Uses oldest costs Uses newest costs
Ending Inventory Value More current value Understated value (older costs)
Tax Liability (Inflation) Higher Lower
GAAP & IFRS Acceptance Universally accepted GAAP (US only), not IFRS
International Use Globally accepted US only
Ease of Use Simple and straightforward Complex; requires separate calculations

LIFO is only permitted as one of the Generally Accepted Accounting Principles (GAAP) in the United States, making it unavailable to international companies. Additionally, LIFO tends to understate the value of closing stock and overstate COGS, which is not accepted by most taxation authorities outside the US. If a company uses the LIFO method, it will need to prepare separate calculations, which calls for additional resources.

Average Cost Method: A Middle Ground

Between FIFO and LIFO lies the average cost method, which offers a compromise approach to inventory valuation. With the average cost method, you calculate the weighted average of all units available for sale during the accounting period and use that average cost to determine the value of COGS and ending inventory.

If FIFO results in the highest net income and LIFO produces the lowest, the average inventory method typically lands somewhere between these two figures. However, this method is more time-consuming to calculate. During inflationary periods, the average cost method might not accurately reflect the current replacement cost of inventory, potentially impacting the valuation of ending inventory and COGS.

FIFO for Different Types of Businesses

FIFO is particularly well-suited for specific business types and industries. The method is ideal for:

Implementing FIFO in Your Business

Implementing the FIFO method involves several steps to ensure compliance and accuracy:

Step 1: Document All Purchases — Maintain detailed records of all inventory purchases, including dates, quantities, and unit costs. This documentation forms the foundation of accurate FIFO calculations.

Step 2: Track Inventory Movement — Monitor which inventory items are sold and in what order. Implement systems that can track the age and cost of inventory items.

Step 3: Calculate COGS Regularly — At the end of each accounting period, calculate your COGS using the FIFO method based on your sales records and inventory costs.

Step 4: Reconcile Inventory — Perform physical inventory counts and reconcile them with your accounting records to identify discrepancies and adjust as needed.

Step 5: Consult with Professionals — Work with accountants and tax advisors to ensure your FIFO implementation complies with GAAP standards and tax regulations.

When to Choose FIFO Over Other Methods

Most businesses benefit from using the FIFO calculation. It’s easy to use, accepted and trusted by investors, lenders, and the IRS, and it follows the natural physical flow of inventory. FIFO is the right choice, especially for businesses that deal in perishable goods, such as restaurants, or any company where inventory obsolescence is a concern.

FIFO is also preferred when your business operates in a stable or deflationary economic environment, when you want to present the most current inventory values on your balance sheet, or when you’re seeking to attract investors by presenting conservative COGS figures and higher net income during non-inflationary periods.

Common Mistakes to Avoid with FIFO

When implementing FIFO, businesses often make several common errors:

Frequently Asked Questions About FIFO

Q: Is FIFO required by law?

A: While not strictly required by law for most US businesses, FIFO is widely accepted and required by IFRS in some international regions. However, companies must choose a consistent inventory method and stick with it for tax compliance purposes.

Q: How does FIFO affect taxes?

A: During inflationary periods, FIFO can result in higher taxable income because older, cheaper inventory costs are matched against current revenue. This typically leads to larger tax bills compared to LIFO, but FIFO is still preferred by the IRS for its transparency.

Q: Can I switch from LIFO to FIFO?

A: Yes, but switching inventory methods requires specific IRS approval and approval through Form 3115 (Application for Change in Accounting Method). The change can have significant tax implications and should only be made after consulting with a tax professional.

Q: What industries use FIFO most commonly?

A: Retail, restaurants, grocery stores, pharmaceuticals, and any business dealing with perishable goods or fashion items use FIFO most commonly. Manufacturing and technology companies also frequently use FIFO.

Q: How is FIFO different from actual inventory flow?

A: FIFO is a cost accounting assumption, not necessarily the physical flow of goods. However, FIFO typically aligns well with how most businesses actually manage inventory, making it both a logical and practical choice.

Q: Does FIFO work during deflation?

A: Yes, FIFO works during deflationary periods, though the tax implications differ from inflation. During deflation, FIFO can result in lower net income compared to LIFO, which might be disadvantageous from a tax perspective.

Conclusion

The FIFO method remains one of the most practical and widely accepted inventory accounting methods available. Its simplicity, alignment with actual inventory practices, and universal acceptance by accounting standards bodies and tax authorities make it an excellent choice for most businesses. Whether you’re running a small retail operation, managing a restaurant’s food inventory, or overseeing manufacturing operations, understanding and implementing FIFO correctly can significantly impact your financial statements and tax position.

While FIFO may not always provide the lowest tax liability during inflationary periods, its transparency, ease of use, and credibility with investors and lenders make it worth serious consideration. Ultimately, the decision between FIFO and other inventory methods depends on your company’s specific circumstances and financial goals. It’s always best to consult with a tax adviser or accountant to determine the most suitable method for your business situation.

References

  1. FIFO and LIFO Accounting for Small Businesses — U.S. Chamber of Commerce. 2024. https://www.uschamber.com/co/run/finance/fifo-vs-lifo
  2. What is FIFO Method in Accounting, and Why is it Important? — Sage. 2024. https://www.sage.com/en-us/blog/glossary/what-is-fifo-method-in-accounting-and-why-is-it-important/

This article is general information, not personal financial advice. Consider your own situation, or speak with a licensed adviser, before acting on it.

Medha Deb
About the author

Medha Deb

Medha Deb writes for BuildTheFund. Every figure is verified against primary sources per our editorial policy.

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