Why Accounting Policy Choices Affect Comparability
Two companies can make similar purchases, use similar equipment, and earn similar sales, yet report different expenses and earnings because they apply different permitted accounting methods. The methods do not necessarily change the underlying transactions or the cash paid. They change how costs are allocated to periods and reported in the financial statements.
Depreciation allocates the cost of a long-lived asset over the periods in which it is used. Inventory-costing methods allocate the cost of goods available for sale between cost of goods sold and ending inventory. In both cases, the method affects current-period expense and an asset’s carrying amount. When expenses differ, reported income differs as well.
A company should apply its chosen policies consistently to similar transactions over time. Consistency helps a reader identify changes in performance rather than changes caused only by a different allocation method. Consistency does not mean every company must use the same policy, nor does it justify keeping a method that no longer reflects the relevant pattern of cost consumption. For comparisons between companies, an analyst may need to understand and, where data allow, adjust for policy differences.
The examples use simplified assumptions: no income taxes, impairment, asset disposals, or other adjustments unless stated. Actual methods and disclosures must follow the applicable reporting framework. For example, FIFO and weighted average are common permitted inventory-costing methods; LIFO is permitted under U.S. GAAP but not under IFRS. A method available under one framework is not automatically available under another.
Depreciation: Allocating an Asset’s Cost
Depreciation expense is an allocation of an asset’s depreciable amount, not a direct measure of its market-value decline. The depreciable amount is cost less estimated residual value. The chosen method should allocate that amount systematically over the asset’s useful life, in a pattern that reflects how the asset’s economic benefits are expected to be consumed.
For cost \(C\), estimated residual value \(R\), and useful life \(n\) years, the straight-line charge for a full year is \((C-R)/n\). Under double-declining balance, the annual rate is \(2/n\), and the preliminary charge is that rate multiplied by the beginning carrying amount. The last charge, or a charge in any year that would otherwise cross the residual-value floor, is limited to the amount needed to bring carrying value to residual value.
Worked Example: Comparing Two Depreciation Methods
A hypothetical company buys equipment for $120,000. It estimates a $20,000 residual value and a five-year useful life. The equipment is available for use for a full year, and the company uses either straight-line or double-declining-balance depreciation. Assume no other adjustments. Calculate depreciation expense and year-end carrying amount for the first two years under each method.
Method and assumptions. The straight-line method allocates the depreciable amount evenly. The double-declining-balance method uses twice the straight-line rate, or \(2/5=40\%\), on beginning carrying value, subject to the $20,000 residual-value floor.
Straight-line. The depreciable amount is \(120{,}000-20{,}000=\$100{,}000\). Annual depreciation is \(100{,}000/5=\$20{,}000\). After year 1, carrying value is \(120{,}000-20{,}000=\$100{,}000\). After year 2, it is \(100{,}000-20{,}000=\$80{,}000\). Thus, each of the first two years has $20,000 of depreciation expense.
Double-declining balance, year 1. The charge is \(40\%\times120{,}000=\$48{,}000\). Year-end carrying value is \(120{,}000-48{,}000=\$72{,}000\).
Double-declining balance, year 2. The charge is \(40\%\times72{,}000=\$28{,}800\). Year-end carrying value is \(72{,}000-28{,}800=\$43{,}200\). Neither charge reduces the asset below residual value.
Check. At the end of year 2, the straight-line carrying amount is $80,000 and the double-declining-balance amount is $43,200. Under each method, cost less accumulated depreciation equals carrying amount: \(120{,}000-40{,}000=80{,}000\) for straight-line and \(120{,}000-76{,}800=43{,}200\) for double-declining balance. The methods allocate different amounts to the first two years, but the total depreciation over the asset’s life cannot exceed $100,000.
Common mistake avoided. Applying \(40\%\) to the original $120,000 cost in both years would incorrectly produce $48,000 in each year. The double-declining rate is applied to the beginning carrying amount; year 2 therefore uses $72,000, not original cost.
Inventory Costing: Allocating Costs Between Expense and Inventory
When identical or interchangeable units are acquired at different costs, a cost-flow assumption determines which costs are assigned to units sold and which remain in ending inventory. It does not necessarily describe the physical movement of units. FIFO assigns the earliest costs to cost of goods sold first; weighted average assigns a common average cost per unit to units sold and units remaining.
For a periodic weighted-average system, calculate the average cost per unit by dividing the total cost of goods available for sale by the total units available. Multiply that average by units sold to find cost of goods sold, and by ending units to find ending inventory. This tutorial uses the periodic approach; a perpetual system may calculate weighted averages at different points during the period.
Worked Example: FIFO and Weighted-Average Inventory
A hypothetical retailer has 100 units in beginning inventory at $10 each, buys 100 units at $14 each, and then buys 100 units at $16 each. During the period it sells 180 units for total revenue of $5,000. Using a periodic inventory system, calculate cost of goods sold, ending inventory, and gross profit under FIFO and weighted average. Assume there are no other costs or adjustments.
Method and units available. Total units available are \(100+100+100=300\). Total cost is \((100\times10)+(100\times14)+(100\times16)=1{,}000+1{,}400+1{,}600=\$4{,}000\). Ending units are \(300-180=120\).
FIFO. The 180 units sold are assigned the earliest costs: \(100\times10=\$1{,}000\), plus \(80\times14=\$1{,}120\). Cost of goods sold is \(1{,}000+1{,}120=\$2{,}120\). Ending inventory contains the remaining 20 units at $14 and 100 units at $16: \((20\times14)+(100\times16)=280+1{,}600=\$1{,}880\). Gross profit is \(5{,}000-2{,}120=\$2{,}880\).
Weighted average. Average cost per unit is \(4{,}000/300=\$13.333333\ldots\). Cost of goods sold is \(180\times13.333333\ldots=\$2{,}400\). Ending inventory is \(120\times13.333333\ldots=\$1{,}600\). Gross profit is \(5{,}000-2{,}400=\$2{,}600\).
Check. Under FIFO, \(2{,}120+1{,}880=\$4{,}000\); under weighted average, \(2{,}400+1{,}600=\$4{,}000\). Both methods allocate the full cost available. Because unit costs rise across the purchases, FIFO assigns more of the recent, higher costs to ending inventory, producing lower cost of goods sold and higher gross profit than weighted average in this example.
Common mistake avoided. The weighted-average cost is based on all 300 units available, not only the 180 units sold. Averaging only the costs of units sold would use the wrong denominator and would not allocate the total cost between sold and remaining units.
Consistency and Fair Comparison
A change in reported expense can arise from a change in business activity, a change in estimates, or a change in accounting policy. These causes should not be confused. A company that reports a different depreciation charge after revising an asset’s useful life has changed an estimate; a company that switches from one depreciation method to another has changed a policy. The accounting treatment and disclosure for a policy change depend on the applicable standards and facts. For analysis, the key first step is to identify what changed and quantify its effect where possible.
Comparing companies also requires attention to the direction of the effect. When purchase costs rise, FIFO generally leaves higher-cost units in ending inventory and assigns lower earlier costs to cost of goods sold than weighted average in a simple periodic comparison. When purchase costs fall, the direction can reverse. For depreciation, an accelerated method generally records more expense earlier and less later than straight-line, assuming the same asset cost, residual value, and useful life. These are allocation patterns, not guarantees about the asset’s economic value or the company’s cash flows.
The following process helps separate reported performance from policy effects:
Determine the depreciation method and inventory-costing method used, and confirm that each is permitted under the applicable reporting framework.
Compare the methods using the same asset cost, useful life, residual value, inventory quantities, purchase costs, and sales.
Calculate the difference in expense and carrying amount, then trace the expense difference to income, assuming other items are unchanged.
If adequate data are available, adjust one set of results to a common method. Otherwise, qualify the comparison and explain which policy differences may affect it.
Worked Example: Normalizing Results Across Two Companies
Two hypothetical companies have the same revenue of $300,000 and other operating expenses of $100,000. Each owns an identical asset costing $90,000, with a $10,000 residual value and five-year useful life. Company A uses straight-line depreciation and FIFO; Company B uses double-declining-balance depreciation and weighted-average inventory costing. In the period being compared, Company A reports depreciation of $16,000 and FIFO cost of goods sold of $90,000. Company B reports depreciation of $36,000 and weighted-average cost of goods sold of $96,000. The underlying inventory records show that applying FIFO to Company B’s inventory would produce cost of goods sold of $90,000. Calculate reported operating income for each and normalize Company B to Company A’s methods. Ignore taxes and other adjustments.
Method. First calculate each reported result as revenue less cost of goods sold, other operating expenses, and depreciation. Then replace Company B’s two method-dependent expenses with the amounts under Company A’s methods.
Company A reported operating income. Subtract cost of goods sold, other operating expenses, and depreciation from revenue: \(300{,}000-90{,}000-100{,}000-16{,}000=\$94{,}000\). Its $16,000 depreciation is also verified by \((90{,}000-10{,}000)/5=\$16{,}000\).
Company B reported operating income. Its reported amount is \(300{,}000-96{,}000-100{,}000-36{,}000=\$68{,}000\).
Normalize Company B. Replacing weighted-average cost of goods sold of $96,000 with FIFO cost of goods sold of $90,000 increases operating income by $6,000. Replacing double-declining-balance depreciation of $36,000 with straight-line depreciation of $16,000 increases it by a further $20,000. Normalized operating income is \(68{,}000+6{,}000+20{,}000=\$94{,}000\). Direct calculation confirms it: \(300{,}000-90{,}000-100{,}000-16{,}000=\$94{,}000\).
Check and interpretation. The reported difference is \(94{,}000-68{,}000=\$26{,}000\), equal to the combined $6,000 inventory-costing effect and $20,000 depreciation effect. On the common-method basis specified in the problem, operating income is equal. This does not prove that the companies are identical in every respect; it shows only that these stated policy differences account for the stated earnings gap.
Common mistake avoided. Comparing reported income without considering the method differences would attribute the full $26,000 gap to underlying performance. The normalization changes only the two specified expenses and leaves revenue and other costs unchanged.
Common Exam Traps and Practical Implications
- Confusing expense allocation with cash flow. A different depreciation charge does not, by itself, change the cash paid for the asset. Different inventory cost allocations likewise do not change the purchase transactions already made.
- Ignoring the balance-sheet effect. Higher depreciation reduces the asset’s carrying amount; higher cost of goods sold generally leaves less inventory on hand. An income-statement comparison alone misses these related asset effects.
- Assuming one method always gives higher earnings. The inventory result depends on the direction of cost changes. The depreciation difference depends on the asset’s period of use and the methods being compared.
- Mixing method choices with estimates. A revised useful life changes the depreciation calculation even if the depreciation method remains the same. Identify whether the method, an estimate, or both changed.
- Rounding too early. In weighted-average calculations, carry the average cost with sufficient precision through the allocation, then round the reported monetary amounts as required.
- Treating consistency as proof of appropriateness. Repeated use of a method supports comparison over time, but the method must still be permitted and appropriate under the applicable reporting framework.
For an analyst, comparability is not achieved by assuming that differently reported earnings are directly equivalent. It requires identifying the methods, understanding the allocation effects, and using a common basis when the information permits. A clear explanation should distinguish the reported result from any analytical adjustment; the adjustment is not itself a replacement for the company’s financial statements.
Check Your Understanding
Work each problem through before checking the answer provided at the end of the question.
- A hypothetical machine costs $75,000, has a residual value of $15,000, and a five-year useful life. It is available for use for a full year. Under straight-line depreciation, what is year 1 expense and year-end carrying amount? (Answer: depreciation expense $12,000; carrying amount $63,000.)
- A hypothetical asset costs $80,000, has a $10,000 residual value, and a four-year useful life. Under double-declining balance, what are the rate, year 1 depreciation, and year 1 ending carrying amount? (Answer: rate 50%; depreciation $40,000; carrying amount $40,000.)
- A periodic inventory system has 40 units at $8 and purchases 60 units at $12. It sells 70 units. Calculate FIFO cost of goods sold and ending inventory. (Answer: cost of goods sold $680; ending inventory $360.)
- A company has 50 units at $20 and purchases 50 units at $28. It sells 60 units for $2,100. Under periodic weighted average, calculate cost of goods sold, ending inventory, and gross profit. (Answer: average cost $24 per unit; cost of goods sold $1,440; ending inventory $960; gross profit $660.)
- Two otherwise comparable firms report operating income of $125,000 and $110,000. The second firm’s depreciation is $9,000 higher and its cost of goods sold is $6,000 higher solely because it uses different methods. What is its operating income after adjustment to the first firm’s methods, assuming all else is unchanged? (Answer: $125,000; add $9,000 and $6,000 to $110,000.)