Inventory is often one of the most significant assets on a company’s balance sheet, therefore is one of the most critical areas to audit. Inventory costing determines how the cost of goods sold (COGS) and ending inventory is calculated. The choice of inventory costing method—whether First-In, First-Out (FIFO), Last-In, First-Out (LIFO), or Weighted Average Cost—can materially affect a company’s profitability, financial position, and tax obligations. Under any selected method, it is important to have consistency because frequent changes can distort the financial performance and comparability.
Auditors must therefore evaluate whether the chosen method is appropriate for the nature of the business and assess whether inventory is recorded fairly, consistently, and in accordance with the applicable accounting framework over the latest audited periods, to avoid future inconsistencies and errors.
FIFO (First-In, First-Out)
Under the FIFO method, the oldest inventory costs are assigned to goods sold first, while the most recent purchases remain in ending inventory. During periods of rising prices, FIFO generally results in lower COGS, higher profits, and a higher inventory valuation on the balance sheet. Because ending inventory reflects more recent acquisition costs, FIFO often provides a valuation closer to current market conditions. However, the resulting higher profits may also increase taxable income. Auditors must verify that FIFO calculations are accurate and that inventory records support the cost flow assumptions applied by management.
LIFO (Last-In, First-Out)
LIFO assumes that the most recently acquired inventory is sold first. During inflation, this typically results in higher COGS and lower reported profits, which can reduce taxable income. However, ending inventory may be valued using older costs that may not be close to market conditions. Auditors reviewing entities that use LIFO must include the disclosures required to explain differences between LIFO and other valuation methods.
Weighted Average Cost Method
The Weighted Average Cost method calculates an average cost per unit based on the total cost of inventory available for sale divided by the total number of units available. This approach smooths the effects of price fluctuations and is particularly suitable when inventory items are homogeneous or interchangeable. Since it produces results that typically fall between FIFO and LIFO, it offers a balanced approach to inventory valuation. Auditors assess whether the averaging process has been calculated correctly and applied consistently over the latest audited periods.
Inventory Obsolescence: A Key Audit Focus
Inventory can become obsolete due to many reasons, some of technological advancements, changing customer preferences, product expiration, or market declines. For a business keeping high inventory amounts, this is very critical. Obsolete or slow-moving inventory must be properly identified and properly reported, to avoid overstating the assets and profitability.
Tools to help Auditor identify such inventory are aging reports, turnover ratios, sales trends, and management’s inventory provisioning policies. Physical inventory inspections may also reveal damaged, expired, or discontinued items that require write-off. Auditors must challenge management’s assumptions regarding future sales and demand forecasts to ensure that provisions for obsolescence are adequate and supported by evidence.
Conclusion
Inventory extends far beyond counting stock. Auditors must assess the appropriateness of costing methodologies, verify valuation accuracy, evaluate obsolescence risks, and understand the tax implications of inventory accounting decisions. Whether a company uses FIFO, LIFO, or Weighted Average Cost, accurate inventory valuation is essential to reliable financial reporting, regulatory compliance, and informed business decision-making. By testing inventory balances and challenging management assumptions where necessary, auditors help ensure that inventory is fairly stated and that stakeholders can rely on the financial information presented with true and fair view.
