Depreciation questions are among the most reliable point-earners on the FAR section of the CPA exam. They appear in multiple-choice questions and task-based simulations, and the examiners love to layer in partial-year conventions, asset disposals, and changes in estimate to test whether you truly understand the mechanics. The good news is that every depreciation method follows a clear, repeatable formula. Once you internalize those formulas and learn to watch for the common traps, you can pick up points quickly and confidently.
This guide walks through every depreciation method you need to know, explains the partial-year conventions that trip up candidates, and shows you how to approach depreciation problems on exam day.
Why Depreciation Matters on the CPA Exam
Depreciation touches several areas of financial accounting. It affects the income statement through depreciation expense, the balance sheet through accumulated depreciation, and the statement of cash flows through the add-back in the indirect method. On the CPA exam, depreciation shows up in standalone calculation questions, but it also appears embedded in larger problems involving asset impairment, disposals, exchanges, and changes in accounting estimate. A solid grasp of the underlying methods makes all of those related topics easier to handle.
Straight-Line Depreciation
Straight-line is the simplest and most commonly used method. It allocates an equal amount of depreciation expense to each period over the useful life of the asset.
Formula: (Cost - Salvage Value) / Useful Life = Annual Depreciation
For example, equipment purchased for $50,000 with a $5,000 salvage value and a 10-year useful life produces annual depreciation of ($50,000 - $5,000) / 10 = $4,500 per year. The depreciable base is always cost minus salvage value, and the expense is the same every single year.
On the exam, straight-line questions become trickier when they involve partial-year conventions or changes in estimate partway through the asset's life. We will cover both of those scenarios later in this guide.
Double Declining Balance (DDB)
Double declining balance is an accelerated method that front-loads depreciation expense into the early years of the asset's life. It ignores salvage value in the annual calculation but never depreciates below salvage.
Formula: (2 / Useful Life) x Book Value at Beginning of Year
Notice that the rate is double the straight-line rate, and you apply it to the beginning book value, not the depreciable base. Using the same example, a $50,000 asset with a 10-year life has a DDB rate of 20%. In year one, depreciation is 20% x $50,000 = $10,000. In year two, the book value is $40,000, so depreciation is 20% x $40,000 = $8,000. This pattern continues, producing progressively smaller charges.
Key exam trap: You must stop depreciating once book value reaches salvage value. If the formula would push book value below salvage, you only depreciate down to salvage. Many candidates forget this rule and choose an answer that over-depreciates.
Sum-of-the-Years-Digits (SYD)
Sum-of-the-years-digits is another accelerated method. It uses a fraction that decreases each year, applied to the depreciable base (cost minus salvage value).
Formula: (Remaining Useful Life / Sum of the Years) x (Cost - Salvage Value)
For a 5-year asset, the sum of the years is 5 + 4 + 3 + 2 + 1 = 15. In year one, the fraction is 5/15. In year two, it is 4/15, and so on. A quick shortcut for computing the sum: n(n+1)/2, where n is the useful life. For 5 years, that is 5(6)/2 = 15.
SYD produces a more gradual acceleration than DDB. It appears less frequently in practice than straight-line or DDB, but the CPA exam still tests it, especially in multiple-choice questions that ask you to compare depreciation expense under different methods.
Units of Production
Units of production ties depreciation to actual usage rather than the passage of time. It is common for manufacturing equipment, vehicles, and other assets whose wear is driven by output.
Formula: (Cost - Salvage Value) / Total Estimated Units x Units Produced in Period
If a machine costs $100,000, has a $10,000 salvage value, and is expected to produce 200,000 units over its life, the per-unit rate is ($100,000 - $10,000) / 200,000 = $0.45 per unit. If the machine produces 30,000 units in year one, depreciation expense is 30,000 x $0.45 = $13,500.
On the exam, units-of-production questions are usually straightforward. The main thing to watch for is whether the problem gives you total estimated units for the life of the asset versus total estimated units remaining. Make sure you use the correct denominator.
MACRS and Tax Depreciation
The Modified Accelerated Cost Recovery System (MACRS) is the depreciation system required for federal income tax purposes in the United States. Unlike GAAP depreciation, MACRS uses prescribed recovery periods, ignores salvage value entirely, and applies specific half-year, mid-quarter, or mid-month conventions.
The most important MACRS concepts for the CPA exam include:
- Recovery periods: Assets are assigned to classes such as 3-year, 5-year, 7-year, 15-year, and 27.5-year or 39-year for real property.
- Half-year convention: Under the default convention, the asset is treated as placed in service at the midpoint of the year, so year-one depreciation is half of a full year's amount.
- Mid-quarter convention: If more than 40% of all depreciable assets placed in service during the year are placed in service in the last quarter, the mid-quarter convention applies instead.
- Section 179 and bonus depreciation: These provisions allow immediate expensing of certain assets, which dramatically reduces or eliminates the need for regular MACRS computations.
- No salvage value: Unlike GAAP methods, MACRS always depreciates the full cost of the asset.
For the CPA exam, you generally do not need to memorize MACRS percentage tables, but you do need to understand the conventions and know when Section 179 or bonus depreciation applies. REG-section questions are more likely to test MACRS details than FAR-section questions.
Partial-Year Conventions
Partial-year conventions are one of the most common ways the CPA exam adds difficulty to depreciation problems. When an asset is purchased partway through the year, you must prorate depreciation for the first and last years of the asset's life.
The three conventions you should know are:
- Exact days or months: Calculate depreciation for the exact number of months the asset was in service. An asset placed in service on April 1 gets 9/12 of a full year's depreciation in year one.
- Half-year convention: Regardless of when the asset is placed in service, it receives half a year of depreciation in the first year and half a year in the last year.
- Nearest full month: Round to the nearest full month. An asset placed in service on or before the 15th of a month gets credit for the full month. After the 15th, it begins the following month.
Exam tip: Always read the problem stem carefully to identify which convention applies. If the problem is silent, the most common assumption on the CPA exam is proration based on exact months.
Changes in Estimate
A change in the estimated useful life or salvage value of an asset is a change in accounting estimate under ASC 250. It is accounted for prospectively, meaning you do not go back and adjust prior periods. Instead, you take the current book value, subtract the new salvage value, and spread the result over the remaining useful life.
For example, suppose equipment originally had a 10-year life and $5,000 salvage. After 4 years under straight-line, accumulated depreciation is $18,000 and book value is $32,000. If the estimate changes to a total life of 12 years with $2,000 salvage, the remaining life is 8 years and annual depreciation becomes ($32,000 - $2,000) / 8 = $3,750.
Changes in estimate are a favorite topic on the CPA exam because they combine depreciation mechanics with knowledge of ASC 250. Watch for problems that embed a change in estimate within a larger scenario.
How to Approach Depreciation Questions on Exam Day
- Identify the method first. Read the entire question before calculating anything.
- Write down the formula for that method so you do not mix up the inputs.
- Check for partial-year conventions and adjust year-one depreciation accordingly.
- Watch for changes in estimate and remember to apply them prospectively.
- If the question asks for accumulated depreciation or book value, build a quick depreciation schedule rather than trying to shortcut the math.
- Double-check whether salvage value is part of the calculation. DDB ignores it in the rate; straight-line and SYD include it in the depreciable base.
Prepare Smarter with Think CPA
Depreciation methods are a foundational FAR topic, and the more comfortable you are with the mechanics, the faster you can move through exam questions. Think CPA provides targeted practice problems for every depreciation method, including partial-year and change-in-estimate scenarios, so you can build speed and accuracy before exam day. If you want structured, exam-focused preparation that takes the guesswork out of studying, explore what Think CPA has to offer.
Final Thoughts
Depreciation is one of the most predictable topics on the CPA exam. The formulas are finite, the conventions are well-defined, and the exam recycled similar question patterns year after year. Invest time in mastering each method, practice with partial-year problems, and learn to recognize changes in estimate. The payoff is reliable, bankable points on exam day.