Difficulty: Intermediate | Prerequisites: Introductory financial accounting (debits/credits, basic financial statements). Familiarity with the periodic vs perpetual inventory distinction is helpful but covered here.
Inventory is one of the largest current assets on a merchandiser's or manufacturer's balance sheet, and the cost flow method a company chooses ripples through cost of goods sold, net income, and taxes. This section of intermediate accounting moves past the introductory "what is inventory" question and into the mechanics of how costs attach to units, how different methods (FIFO, LIFO, weighted-average) change reported results, and how shipping terms and consignment arrangements determine who actually owns the goods at a given moment. If you are comfortable with basic journal entries for purchases and sales, you have enough to follow along. The material here maps to the inventory and cost-of-goods-sold chapters of most intermediate textbooks and is heavily tested.
The inventory cost flow assumption you pick (FIFO, LIFO, or weighted-average) determines which costs sit on the balance sheet and which flow to cost of goods sold. LIFO is the tax-minimiser when prices rise; FIFO gives a balance sheet closer to current costs. Ownership of goods turns on FOB terms and consignment status, not physical possession.
FIFO (First-In, First-Out)
The oldest costs in inventory are assigned to cost of goods sold first. In simple terms, this means the goods you bought earliest are treated as the goods you sold earliest, leaving the most recent costs on the balance sheet.
LIFO (Last-In, First-Out)
The most recent costs are assigned to cost of goods sold first. Think of it as reaching for the newest items on the shelf, so the balance sheet retains older, often lower, costs.
Weighted-Average Cost
A blended unit cost calculated by dividing the total cost of goods available for sale by the total quantity available. In simple terms, every unit carries the same average cost, smoothing out price swings.
Cost of Goods Sold (COGS)
The direct cost of inventory that a company has sold during a period. Calculated as Beginning Inventory + Net Purchases - Ending Inventory.
Net Purchases
Total purchases adjusted for returns, discounts, and freight-in. Formula: Total Purchases + Freight and Other Costs - Purchase Returns and Discounts.
Net Realisable Value (NRV)
Estimated selling price in the ordinary course of business, minus the costs of completion, disposal, and transportation. Think of it as the amount you would actually pocket after finishing and selling the item.
LIFO Reserve
The difference between inventory valued at FIFO and inventory valued at LIFO. An increase in the LIFO reserve reduces reported profits; a decrease increases them.
LIFO Liquidation
Occurs when a company using LIFO sells more units than it purchases, dipping into older, lower-cost layers. This happens when costs are rising and inventory quantity declines, inflating reported profits.
Dollar-Value LIFO
A variation of LIFO that groups inventory into pools measured in total dollar amounts rather than individual units. Simplifies record keeping and reduces the risk of LIFO layer liquidation.
Consignee
Someone who holds goods on behalf of the owner (the consignor) but does not have title. The goods remain in the consignor's inventory until the consignee sells them.
FOB Destination
The seller is responsible for shipping; title does not transfer to the buyer until the goods arrive at the buyer's location.
FOB Shipping Point
The buyer is responsible for shipping; title transfers to the buyer once the goods are handed to the carrier.
Gross Profit Ratio
Gross Profit divided by Net Sales. Measures the percentage of each sales pound retained after covering the direct cost of the goods.
Inventory Turnover Ratio
Cost of Goods Sold divided by Average Inventory. Indicates how many times a company sells and replaces its inventory during a period.
Perpetual Inventory System
Inventory records are updated continuously with each purchase and sale. When merchandise is returned to a supplier, the Inventory account is credited directly.
Periodic Inventory System
Inventory is counted and costed only at the end of the period. Under FIFO, the perpetual and periodic systems produce the same ending inventory and COGS figures.
FIFO assigns the earliest costs to COGS. In a period of declining costs, FIFO produces the lowest ending inventory (older, higher costs go to COGS first) and the lowest net income.
LIFO assigns the most recent costs to COGS. In a period of declining costs, LIFO produces the highest ending inventory because the cheaper recent purchases flow out first, leaving the older, higher-cost layers on the balance sheet.
Weighted-average blends all costs together. The unit cost equals total cost of goods available for sale divided by total quantity available for sale.
Under FIFO, the perpetual and periodic systems yield identical ending inventory and COGS. Under LIFO and weighted-average, results can differ between the two systems.
Net method: Inventory is recorded at the discounted price from the start. If the discount window lapses, the extra amount is booked as Interest Expense (a financing cost for paying late).
Gross method: Inventory is recorded at the full invoice price. If the discount is not taken, the entry stands as Purchases. Discounts taken reduce the Purchases balance.
When goods are returned to a supplier under a perpetual system, the Inventory account is credited directly, reducing the asset on the books.
FOB destination: The seller bears shipping costs and risk. Title passes when the goods arrive at the buyer's location, so goods in transit at period-end belong to the seller.
FOB shipping point: The buyer bears shipping costs and risk. Title passes when the goods reach the carrier. Goods in transit at period-end belong to the buyer.
Freight-in cost, when the purchaser is responsible, is usually included in the cost of inventory.
Goods held on consignment remain in the consignor's inventory, not the consignee's. The consignee is simply holding the goods for sale. The goods stay in the consignor's records until the consignee sells them.
When a LIFO company's purchases fall short of sales, it dips into older, cheaper inventory layers. If costs have been rising, these old layers carry low costs, which depresses COGS and inflates profit, a phenomenon called a LIFO liquidation profit. The trigger: costs are rising and inventory quantity declines.
The LIFO reserve is the gap between inventory under FIFO and inventory under LIFO. An increase in the LIFO reserve means LIFO COGS exceeded FIFO COGS, reducing reported profits. A decrease in the LIFO reserve means the opposite, increasing reported profits. Companies must disclose the inventory method they use.
LIFO inventory pools group units with similar physical characteristics into a single pool, simplifying record keeping and reducing the chance of accidental LIFO liquidation. Dollar-value LIFO takes this further by measuring the pool in total dollars rather than individual units, using a cost index to separate real quantity changes from price changes.
Cost index formula: Cost in layer year / Cost in base year.
A dollar-value LIFO pool is made up of items likely to face the same cost-change pressure.
Companies are required to disclose the inventory method they use. This is not optional.
COGS = Beginning Inventory + Net Purchases - Ending Inventory
Net Purchases = Total Purchases + Freight-In and Other Costs - Purchase Returns and Discounts
Net Realisable Value (NRV) = Estimated Selling Price - Costs of Completion, Disposal, and Transportation
Weighted-Average Unit Cost = Cost of Goods Available for Sale / Quantity Available for Sale
Gross Profit Ratio = Gross Profit / Net Sales
Inventory Turnover Ratio = Cost of Goods Sold / Average Inventory
Cost Index (Dollar-Value LIFO) = Cost in Layer Year / Cost in Base Year
Students often think companies choose FIFO to minimise taxes when prices are rising. They do not. Companies choose LIFO in that scenario because it assigns the higher, more recent costs to COGS, lowering taxable income.
Students often confuse physical possession with ownership. A consignee physically holds the goods, but the consignor retains title. Goods on consignment stay in the consignor's inventory.
Students sometimes assume that perpetual and periodic systems always produce the same results. They do under FIFO, but not necessarily under LIFO or weighted-average.
Students often think companies can stay quiet about their inventory method. Disclosure of the inventory method is required.
⚠️ Know the effect of each cost flow method on ending inventory AND COGS under both rising and declining cost scenarios. This is a near-certain exam question.
⚠️ LIFO liquidation profits: be ready to explain when they occur (rising costs + falling quantities) and why they inflate income.
⚠️ Net method vs gross method: know which account is debited when a discount is missed under each approach (Interest Expense for net, Purchases for gross).
⚠️ FOB terms: expect a question asking who owns goods in transit at period-end.
⚠️ The LIFO reserve adjustment: an increase reduces profits, a decrease increases profits. This direction trips students up.
True or False: Under LIFO, when prices are rising, ending inventory is valued at the most recent costs. (False, ending inventory retains the oldest costs.)
Fill in the blank: COGS = Beginning Inventory + ______ - Ending Inventory. (Net Purchases)
True or False: Goods on consignment are included in the consignee's inventory. (False, they remain in the consignor's inventory.)
Fill in the blank: Under the net method, a discount not taken is recorded as ______. (Interest Expense)
True or False: An increase in the LIFO reserve increases reported profits. (False, it reduces reported profits.)
Q: In a period of declining costs, which inventory cost method produces the highest ending inventory?
A: LIFO. When costs are declining, the most recent (cheaper) costs flow to COGS under LIFO, leaving the older, higher costs in ending inventory.
Q: Under the gross method, how is a purchase discount not taken recorded?
A: It is recorded as Purchases (the full invoice amount stays on the books with no adjustment).
Q: When do LIFO liquidation profits occur?
A: When costs are rising and inventory quantity declines, forcing the company to dip into older, lower-cost LIFO layers.
Q: If goods are shipped FOB shipping point, who owns the goods while they are in transit?
A: The buyer. Title transfers when the goods reach the carrier.
Q: What is the formula for net realisable value?
A: NRV = Estimated Selling Price - Costs of Completion, Disposal, and Transportation.
Q: Will ending inventory and COGS be the same under perpetual and periodic systems when FIFO is used?
A: Yes. FIFO produces identical results under both systems.
Q: What is the purpose of LIFO inventory pools?
A: To simplify record keeping by grouping units with similar physical characteristics and to reduce the risk of LIFO layer liquidation.
Inventory valuation feeds directly into the income statement through COGS and into the balance sheet as a current asset, so the method chosen here changes every downstream ratio that depends on net income or total assets. This connects to the financial statement analysis topics (profitability and efficiency ratios) and to the tax-planning material covered in later chapters. The ownership and transfer-of-title rules also tie into revenue recognition, since revenue cannot be recognised until risks and rewards of ownership have passed to the buyer.
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