LIFO vs FIFO Inventory Methods: Which Should You Use?

Written by Calvin Lo, Founder of Aphelios Software | July 2026

LIFO and FIFO are two of the most commonly used inventory valuation methods, but they work in completely opposite ways. Choosing the right method affects your reported profit, tax liability, stock rotation and financial reporting.

This guide explains how each method works, compares their advantages and disadvantages, and helps you decide which approach suits your business.

What Is FIFO Inventory Management?

FIFO stands for First In First Out. Under this method, the oldest inventory items (the first ones purchased or produced) are sold or used first.

FIFO aligns with the natural flow of most physical goods. Products that have been in stock the longest leave the warehouse first, reducing the risk of expired or obsolete inventory.

In periods of rising prices, FIFO results in lower cost of goods sold (COGS) and higher reported profits, because older, cheaper inventory is matched against current revenue.

What Is LIFO Inventory Management?

LIFO stands for Last In First Out. Under this method, the newest inventory items (the most recently purchased or produced) are sold or used first.

LIFO does not match the physical flow of most goods — you would rarely sell your freshest stock while leaving older stock sitting on the shelf. However, during periods of inflation, LIFO produces a higher COGS and lower taxable income, which can be beneficial for tax purposes in jurisdictions where it is permitted.

Important: LIFO is not permitted under UK GAAP (FRS 102) or IFRS accounting standards. UK businesses must use FIFO or weighted average cost for statutory financial reporting.

LIFO vs FIFO: Key Differences

Example: LIFO vs FIFO in Action

Imagine you sell a product and make three purchases:

• Batch 1: 100 units at £10 each
• Batch 2: 100 units at £12 each
• Batch 3: 100 units at £15 each

You sell 150 units. Here is how COGS differs under each method:

In this example, FIFO produces a lower COGS (£1,600 vs £2,100), meaning higher reported profit. LIFO produces higher COGS and lower profit — which could reduce tax liability in countries where LIFO is allowed.

Advantages of FIFO

• Matches physical stock flow for most businesses
• Reduces waste from expired or obsolete inventory
• Compliant with UK GAAP and IFRS
• Higher inventory valuation on balance sheet
• Simpler to implement and audit
• Preferred by HMRC for UK tax reporting

Disadvantages of FIFO

• Higher reported profit means higher taxable income
• COGS may not reflect current replacement costs during inflation
• Requires good batch tracking and stock rotation processes

Advantages of LIFO

• Lower taxable profit during inflationary periods (where permitted)
• COGS more closely matches current replacement costs
• Useful for commodity businesses with volatile prices

Disadvantages of LIFO

• Not permitted under UK GAAP or IFRS
• Does not match physical stock flow for most businesses
• Increases risk of aged or obsolete inventory
• Lower inventory valuation on balance sheet
• More complex to maintain and audit
• Can distort financial comparisons over time

Which Method Should UK Businesses Use?

For UK businesses, the choice is straightforward: FIFO is the standard method required under UK GAAP (FRS 102) and IFRS. LIFO cannot be used for statutory reporting.

Most UK businesses also find FIFO aligns better with their physical operations. Selling older stock first reduces waste, improves cash flow, and ensures customers receive fresher products.

The alternative to FIFO in the UK is the weighted average cost method, which smooths out price fluctuations by averaging the cost of all similar items in stock.

Modern inventory management software with barcode scanning automates FIFO enforcement, batch tracking and cost calculations, ensuring your inventory valuation is always accurate and compliant.

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