Depreciation Methods: GAAP vs. Tax Rules

Introduction to Depreciation Methods

Depreciation is a fundamental accounting concept used to allocate the cost of a tangible asset over its useful life. For candidates preparing to take the CPA Exam, mastering various depreciation methods is essential for passing multiple sections of the exam. The way an asset is depreciated depends heavily on whether the reporting is for financial statements or tax purposes. Financial accounting focuses on matching expenses with revenues, while tax accounting focuses on statutory rules and economic incentives.

When preparing your study schedule, it is important to understand how these concepts are divided across the CPA exam sections. Financial accounting depreciation is a core topic in the Financial Accounting and Reporting (FAR) section. Conversely, tax depreciation rules are heavily tested in the Regulation (REG) section. Understanding the differences between these two frameworks will help you avoid confusing GAAP rules with IRS regulations during your exam preparation.

Financial Accounting (GAAP) Depreciation Methods

For financial reporting under US GAAP, common depreciation methods include straight-line, declining-balance, sum-of-the-years'-digits, and units-of-production. These methods are designed to reflect the economic consumption of the asset's utility over time. According to the SEC Investor Bulletin: How to Read a Financial Statement, companies must disclose their depreciation methods and the estimated useful lives of their assets in the footnotes to their financial statements.

The straight-line method is the simplest and most widely used approach. It distributes an equal amount of depreciation expense to each year of the asset's useful life. To calculate straight-line depreciation, you subtract the asset's salvage value from its historical cost and divide the result by the useful life. This method is ideal for assets that provide equal utility throughout their operational lifespan.

Accelerated methods, such as the double-declining balance and sum-of-the-years'-digits, allocate higher depreciation expenses to the early years of an asset's life. The double-declining balance method applies a constant rate (typically twice the straight-line rate) to the declining book value of the asset. Candidates must remember not to subtract the salvage value from the initial book value when calculating the annual depreciation, though the asset cannot be depreciated below its salvage value. You can practice these calculations using our free CPA practice test to ensure you understand the mechanics.

The units-of-production method bases depreciation on the actual physical usage of the asset rather than the passage of time. This method is highly relevant for machinery or vehicles where wear and tear are directly tied to output. To master these GAAP calculations, candidates should regularly work through CPA practice questions to build speed and accuracy for the FAR exam.

Tax Depreciation: The MACRS Framework

For US federal income tax purposes, businesses must generally use the Modified Accelerated Cost Recovery System (MACRS) to depreciate tangible property placed in service after 1986. This system is governed by the Internal Revenue Service (IRS) and differs significantly from GAAP. MACRS is designed to simplify tax reporting and provide accelerated tax write-offs to encourage business investment.

According to IRS Publication 946, MACRS consists of two depreciation systems: the General Depreciation System (GDS) and the Alternative Depreciation System (ADS), which dictate recovery periods and depreciation methods. GDS is the most common system used by taxpayers, while ADS is required for certain properties, such as property used predominantly outside the United States or tax-exempt use property.

Under MACRS GDS, standard depreciation methods include the 200% declining balance method, the 150% declining balance method, and the straight-line method. The IRS assigns specific recovery periods (such as 3, 5, 7, 15, or 20 years) to different classes of property. For example, office furniture and equipment are typically classified as 7-year property, while automobiles are classified as 5-year property.

Real property has its own specific rules under MACRS. Under MACRS GDS, nonresidential real property is generally depreciated over a 39-year recovery period using the straight-line method and a mid-month convention. Residential rental property, on the other hand, is depreciated over 27.5 years. Candidates must pay close attention to these recovery periods and conventions when solving tax problems on the REG exam.

Section 179 Expensing and Bonus Depreciation

In addition to standard MACRS depreciation, the tax code provides immediate expensing options to help businesses reduce their taxable income quickly. Under IRS rules, Section 179 allows taxpayers to elect to expense the cost of certain qualifying business property in the year it is placed in service, rather than depreciating it over time. This is a powerful tool for small and medium-sized businesses looking to write off the full cost of equipment immediately.

Section 179 is subject to annual dollar limits and investment limitations. If a business purchases too much qualifying property during the tax year, the deduction begins to phase out dollar-for-dollar. Additionally, the Section 179 deduction cannot exceed the taxable income derived from the active conduct of any trade or business during the year. Any disallowed portion can be carried forward to future tax years.

Bonus depreciation is another tax incentive that allows businesses to immediately deduct a percentage of the cost of qualifying assets. Unlike Section 179, bonus depreciation does not have a taxable income limitation and is not restricted to small businesses. Candidates must understand how Section 179 and bonus depreciation interact with standard MACRS calculations to correctly determine a business's tax liability.

CPA Exam Testing: FAR vs. REG

The CPA Exam tests financial accounting depreciation methods (such as straight-line and double-declining balance) under the FAR section, while tax depreciation under MACRS and Section 179 is tested under the REG section. This clear division means you must adapt your mindset depending on which exam you are taking. Mixing up GAAP and tax rules is a common pitfall for many candidates.

When studying for FAR, focus on the matching principle, salvage value, and financial statement disclosures. When studying for REG, focus on IRS recovery periods, MACRS conventions (half-year, mid-quarter, and mid-month), and statutory limits for Section 179. Utilizing structured CPA study tips can help you keep these rules organized.

To optimize your study schedule, consider using a CPA study planner. Allocating dedicated study blocks to practice both GAAP and tax depreciation calculations will ensure you are prepared for any simulation or multiple-choice question on exam day. Consistent practice is the key to mastering these highly tested concepts.

Frequently asked questions

Sources

• IRS Publication 946 (retrieved 2026-07-09)
• SEC Investor Bulletin: How to Read a Financial Statement (retrieved 2026-07-09)
• IRS Tax Topics - Topic No. 704 Depreciation (retrieved 2026-07-09)
• AICPA & CIMA CPA Exam Resources (retrieved 2026-07-09)