Depreciation Methods: Straight-Line, Declining Balance, and More
Calculate asset depreciation using straight-line, declining balance, sum-of-years-digits, and units of production methods. Understand tax depreciation and MACRS.
What Is Depreciation?
Depreciation is the systematic allocation of an assets cost over its useful life. Rather than expensing the full purchase price in the year of acquisition, depreciation spreads the cost across the years the asset generates revenue. This matching principle — aligning expenses with the revenue they help produce — is fundamental to both accurate financial reporting and tax compliance.
Under most accounting frameworks, tangible assets such as machinery, vehicles, buildings, computers, furniture, and equipment are depreciated. Land is not depreciable because it does not wear out or get consumed over time. Intangible assets like patents and copyrights are amortized rather than depreciated, following similar principles but different rules.
Straight-Line Depreciation Method
The straight-line method is the simplest and most commonly used depreciation method. It allocates an equal amount of depreciation expense each year over the assets useful life. The formula is: Annual Depreciation = (Cost — Salvage Value) ÷ Useful Life. A $50,000 machine with a $5,000 salvage value and 10-year useful life depreciates at ($50,000 — $5,000) ÷ 10 = $4,500 per year.
Swipe sideways to compare columns.
| Year | Beginning Book Value | Depreciation Expense | Accumulated Depreciation | Ending Book Value |
|---|---|---|---|---|
| 1 | $50,000 | $4,500 | $4,500 | $45,500 |
| 2 | $45,500 | $4,500 | $9,000 | $41,000 |
| 3 | $41,000 | $4,500 | $13,500 | $36,500 |
| 4 | $36,500 | $4,500 | $18,000 | $32,000 |
| 5 | $32,000 | $4,500 | $22,500 | $27,500 |
| 6 | $27,500 | $4,500 | $27,000 | $23,000 |
| 7 | $23,000 | $4,500 | $31,500 | $18,500 |
| 8 | $18,500 | $4,500 | $36,000 | $14,000 |
| 9 | $14,000 | $4,500 | $40,500 | $9,500 |
| 10 | $9,500 | $4,500 | $45,000 | $5,000 |
Straight-line depreciation is best for assets that provide consistent value over their lifetime — buildings, office furniture, long-term infrastructure. Its simplicity makes it easy to calculate and audit. The primary disadvantage is that it does not reflect the actual pattern of economic decline for assets that lose more value in early years.
Declining Balance (Accelerated) Method
The declining balance method accelerates depreciation, recording higher expenses in early years and lower expenses later. This matches the economic reality of many assets — vehicles, computers, and machinery lose more value in their first years of use. The formula is: Depreciation Expense = Book Value at Beginning of Year × Depreciation Rate.
The most common variant is double declining balance (DDB), which uses twice the straight-line rate. For a 10-year asset, the straight-line rate is 10%, so the DDB rate is 20%. Unlike straight-line, declining balance ignores salvage value in the annual calculation — but the asset should not be depreciated below its salvage value.
Swipe sideways to compare columns.
| Year | DDB Depreciation | DDB Book Value | Straight-Line Depreciation | SL Book Value |
|---|---|---|---|---|
| 1 | $10,000 | $40,000 | $4,500 | $45,500 |
| 2 | $8,000 | $32,000 | $4,500 | $41,000 |
| 3 | $6,400 | $25,600 | $4,500 | $36,500 |
| 4 | $5,120 | $20,480 | $4,500 | $32,000 |
| 5 | $4,096 | $16,384 | $4,500 | $27,500 |
| 6 | $3,277 | $13,107 | $4,500 | $23,000 |
| 7 | $2,621 | $10,486 | $4,500 | $18,500 |
| 8 | $2,097 | $8,389 | $4,500 | $14,000 |
| 9 | $1,678 | $6,711 | $4,500 | $9,500 |
| 10 | $1,342 | $5,369 | $4,500 | $5,000 |
DDB results in total depreciation of $44,631 over 10 years (compared to $45,000 straight-line). The difference reflects the salvage value floor. Many companies switch from DDB to straight-line when the straight-line amount exceeds the DDB amount for a given year, maximizing depreciation within the assets useful life.
Sum-of-the-Years-Digits Method
SYD is another accelerated depreciation method. It applies a decreasing fraction each year based on the sum of the years digits. For a 5-year asset, the sum is 5+4+3+2+1 = 15. Year 1 depreciation is 5/15 of the depreciable base, Year 2 is 4/15, and so on. The formula is: Depreciation Expense = (Cost — Salvage) × (Remaining Life ÷ SYD).
SYD produces a smoother acceleration pattern than DDB. In the first year of a 10-year, $50,000 asset ($5,000 salvage), the SYD is 10+9+8+7+6+5+4+3+2+1 = 55. Year 1 depreciation = $45,000 × (10 ÷ 55) = $8,182. Year 10 = $45,000 × (1 ÷ 55) = $818. This falls between straight-line and DDB in terms of front-loading.
Units of Production Method
Units of production ties depreciation to actual usage rather than time. This method is ideal for manufacturing equipment, vehicles, and assets where wear and tear depends on output rather than calendar years. The formula is: Depreciation per Unit = (Cost — Salvage Value) ÷ Estimated Total Units. Depreciation Expense = Depreciation per Unit × Units Produced in Period.
A $50,000 machine expected to produce 100,000 units with $5,000 salvage has a per-unit rate of ($50,000 — $5,000) ÷ 100,000 = $0.45 per unit. If the machine produces 12,000 units in Year 1, depreciation is 12,000 × $0.45 = $5,400. If it produces 8,000 units in Year 2, depreciation is 8,000 × $0.45 = $3,600. This method provides the best matching of expense to revenue but requires accurate production tracking.
MACRS: Tax Depreciation in the United States
The Modified Accelerated Cost Recovery System is the tax depreciation method required by the IRS for most business assets placed in service after 1986. MACRS assigns assets to property classes with predetermined recovery periods (e.g., 5 years for computers and vehicles, 7 years for office furniture and equipment, 39 years for nonresidential real estate). Each class has a prescribed depreciation table that combines declining balance with an automatic switch to straight-line.
MACRS generally provides faster depreciation than book methods, reducing taxable income more in the early years of an assets life. Bonus depreciation and Section 179 expensing allow businesses to deduct a significant portion (often 100%) of an assets cost in the first year, subject to limits and phaseouts. These provisions are periodically updated by tax legislation.
Businesses typically maintain two depreciation schedules: book depreciation (usually straight-line) for financial reporting under GAAP or IFRS, and tax depreciation (MACRS) for IRS filings. The difference between the two creates deferred tax liabilities or assets on the balance sheet.
Calculate Asset Depreciation
Depreciation CalculatorUse our Depreciation Calculator to compare straight-line, declining balance, SYD, and units of production methods for any business asset.Frequently Asked Questions
Which depreciation method should I use for financial reporting?
Most companies use straight-line for financial reporting because it is simple and produces consistent expenses. Use accelerated methods if the asset generates more revenue in early years. For tax purposes, you must use MACRS for US federal taxes. Many businesses use straight-line for book reporting and MACRS for tax reporting.
Can I change depreciation methods for an existing asset?
Changes in depreciation method are considered a change in accounting estimate, requiring disclosure. Under GAAP, you can change methods if the new method better reflects the economic benefit pattern of the asset. Method changes typically require approval from auditors and may have tax implications.
What happens when I sell a depreciated asset?
If the selling price exceeds the book value, the gain is recognized as income. If the selling price is below book value, the loss may be deductible. Tax treatment differs for Section 1231 assets, Section 1245 recapture (which treats gain as ordinary income up to prior depreciation), and Section 1250 real estate. Consult a tax professional for specific guidance.