LIFO Inventory Method: What It Is, How It Works, and When to Use It

If your business carries inventory, the method you use to value that inventory directly affects your tax bill, your reported profits, and your balance sheet. The Last In, First Out (LIFO) method is one of the most powerful—and most misunderstood—inventory valuation strategies available to U.S. businesses.

With rising costs driven by inflation and new tariffs in recent years, LIFO has gained renewed attention as a legitimate tax-saving tool. Here's everything you need to know about how it works, when it makes sense, and what to watch out for.

What Is the LIFO Method?

LIFO stands for Last In, First Out. It's an inventory valuation method that assumes the most recently purchased or produced items are sold first.

This doesn't mean you physically ship your newest stock before your oldest. LIFO is purely an accounting assumption—a cost flow method used to calculate your Cost of Goods Sold (COGS) and the value of your remaining inventory.

Under LIFO, the cost of your most recent purchases gets matched against your current revenue. The older, often cheaper inventory costs remain on your balance sheet as ending inventory.

How LIFO Works: A Step-by-Step Example

Imagine you run a hardware store and purchase wrenches in three batches over a quarter:

Purchase	Units	Cost Per Unit	Total Cost
January	100	$8.00	$800
February	100	$9.00	$900
March	100	$10.00	$1,000

You now have 300 wrenches in stock at a total cost of $2,700. During the quarter, you sell 200 wrenches.

Under LIFO, you assume the 200 most recently purchased wrenches were sold first:

• 100 units from March at $10.00 = $1,000
• 100 units from February at $9.00 = $900
• COGS = $1,900
• Ending inventory = 100 units from January at $8.00 = $800

Under FIFO (First In, First Out), you'd assume the oldest inventory sold first:

• 100 units from January at $8.00 = $800
• 100 units from February at $9.00 = $900
• COGS = $1,700
• Ending inventory = 100 units from March at $10.00 = $1,000

Notice the difference: LIFO produces a higher COGS ($1,900 vs. $1,700) and lower ending inventory ($800 vs. $1,000) when costs are rising. That higher COGS means lower taxable income—and a smaller tax bill.

LIFO vs. FIFO: Key Differences

Factor	LIFO	FIFO
Cost flow assumption	Newest costs to COGS	Oldest costs to COGS
COGS when prices rise	Higher	Lower
Net income when prices rise	Lower	Higher
Tax liability when prices rise	Lower	Higher
Ending inventory valuation	Based on oldest costs	Based on newest costs
Balance sheet accuracy	Less reflective of current values	More reflective of current values
Allowed under GAAP	Yes	Yes
Allowed under IFRS	No	Yes

The choice between LIFO and FIFO isn't just academic—it can mean thousands or even millions of dollars in tax differences for inventory-heavy businesses.

Why Businesses Choose LIFO

1. Tax Savings During Inflation

This is the primary reason most businesses adopt LIFO. When costs are rising, LIFO assigns higher recent costs to COGS, which reduces taxable income. The tax savings are real and can be substantial.

For example, a petroleum distributor facing fuel cost increases of 15–20% per year could save hundreds of thousands in taxes annually by using LIFO instead of FIFO.

2. Better Revenue-Cost Matching

LIFO matches your most recent costs against your current revenue. This gives a more accurate picture of your current operating margins because the costs on your income statement reflect what you're actually paying for inventory today—not what you paid months or years ago.

3. Improved Cash Flow

Lower tax payments mean more cash stays in your business. That improved cash flow can be reinvested in operations, used to pay down debt, or held as a buffer against economic uncertainty.

4. Tariff and Trade Protection

With new tariffs driving up the cost of imported goods, LIFO has become an especially attractive option. Businesses importing raw materials or finished goods subject to tariffs can use LIFO to offset some of the cost impact through reduced tax liability.

The Drawbacks of LIFO

1. Lower Reported Profits

The same mechanism that saves you on taxes also reduces your reported net income. If you're seeking investors, applying for loans, or trying to demonstrate profitability, LIFO can make your financials look less attractive.

2. Outdated Balance Sheet Values

Because ending inventory under LIFO is valued at the oldest costs, your balance sheet may significantly understate the true market value of your inventory. Over many years, this gap—called the LIFO reserve—can grow quite large.

3. LIFO Conformity Rule

The IRS requires that if you use LIFO for tax purposes, you must also use it for financial reporting (your income statement and balance sheet provided to shareholders, banks, and creditors). You can't use LIFO for taxes and FIFO for your financial statements.

4. Not Allowed Under IFRS

LIFO is prohibited under International Financial Reporting Standards (IFRS). If your business operates internationally, reports to foreign investors, or is considering an international merger or acquisition, LIFO creates complications. Companies switching away from LIFO to comply with IFRS may face significant tax consequences from recapturing the LIFO reserve.

5. LIFO Liquidation Risk

LIFO liquidation happens when you sell more units than you purchase in a given period, forcing you to dip into older, lower-cost inventory layers. This artificially inflates profits and triggers a larger tax bill—the opposite of what LIFO is designed to do.

For example, if a supply chain disruption prevents you from restocking and you sell through old inventory purchased at much lower costs, your reported profits spike even though your actual business performance hasn't improved.

Understanding the LIFO Reserve

The LIFO reserve is the difference between what your inventory would be worth under FIFO and its current LIFO value:

LIFO Reserve = FIFO Inventory Value − LIFO Inventory Value

This number is important for several reasons:

• Analysts use it to compare LIFO companies with FIFO companies on an apples-to-apples basis
• It represents deferred taxes—if you ever switch away from LIFO, you'll owe taxes on this amount
• It reveals the cumulative effect of using LIFO over time

A company with a $5 million FIFO inventory value and a $3.5 million LIFO inventory value has a LIFO reserve of $1.5 million. At a 25% tax rate, that represents $375,000 in deferred tax liability.

Which Businesses Benefit Most from LIFO?

LIFO tends to work best for:

• Oil and gas companies dealing with volatile commodity prices
• Manufacturing businesses with rising raw material costs (metals, chemicals, construction materials)
• Distributors and wholesalers facing inflationary pressures on large inventory volumes
• Retailers with non-perishable goods where inventory doesn't expire or become obsolete
• Importers subject to tariffs that increase landed costs over time

LIFO is generally not a good fit for:

• Businesses with perishable inventory (food, pharmaceuticals)
• Companies with declining costs (technology products that get cheaper over time)
• Businesses with international reporting requirements under IFRS
• Small businesses with minimal inventory where the accounting complexity isn't worth the savings

How to Adopt LIFO

Switching to LIFO requires filing IRS Form 3115 (Application for Change in Accounting Method). Key considerations:

1. Timing matters: The decision must be made before you file your tax return and issue financial statements for the year you want to start using LIFO
2. It's prospective: You apply LIFO going forward from the date of adoption—you can't go back and recapture benefits from prior periods
3. Consistency is required: Once you adopt LIFO, you must use it consistently. Switching back requires another Form 3115 filing and may trigger tax on the LIFO reserve
4. Professional guidance recommended: Work with a CPA or tax advisor who has experience with LIFO elections, as the rules around dollar-value LIFO pools, index calculations, and conformity requirements are complex

Other Inventory Valuation Methods

If LIFO doesn't fit your business, consider these alternatives:

• FIFO (First In, First Out): Assumes oldest inventory sells first. Best when you want higher asset values on the balance sheet or when inventory costs are declining.
• Weighted Average Cost: Calculates a blended average cost for all units available for sale. Simpler to maintain and smooths out cost fluctuations.
• Specific Identification: Tracks the actual cost of each individual item. Best for high-value, unique items like vehicles, jewelry, or art.

Keep Your Inventory Accounting Organized

Whether you choose LIFO, FIFO, or another method, accurate inventory tracking is the foundation of sound financial management. The wrong method—or sloppy record-keeping—can cost you thousands in overpaid taxes or lead to misleading financial statements.

Beancount.io provides plain-text accounting that gives you complete transparency over your inventory costs, COGS calculations, and financial reports. With version-controlled records and AI-ready data, you can track every inventory layer with confidence. Get started for free and take control of your financial data.