Straight-Line Depreciation

Straight-line depreciation is an accounting method that spreads the cost of a tangible asset evenly across its useful life. Each year, the same fixed amount is deducted from the asset's value until it reaches its salvage value or zero. It is the most widely used depreciation method for both financial reporting and tax purposes.

How straight-line depreciation works

The formula requires three inputs: the asset's original cost, its estimated salvage value, and its useful life in years.

Annual depreciation expense = (Cost − salvage value) ÷ useful life

For example, equipment purchased for $50,000 with a $5,000 salvage value and a 10-year useful life depreciates at $4,500 per year. That amount is recorded on the income statement annually and reduces the asset's book value on the balance sheet by the same amount each year.

Why it matters

Straight-line depreciation ensures that the cost of an asset is recognized over the period it generates economic benefit, rather than all at once in the year of purchase. This aligns with the matching principle in accrual accounting.

The IRS allows businesses to depreciate most tangible assets, and straight-line depreciation is an accepted method under the Modified Accelerated Cost Recovery System (MACRS). The IRS requires it for residential rental property (27.5-year life) and commercial real estate (39-year life). Depreciation also affects financial statements used for business loans, investor reporting, and entity compliance.

Key characteristics and limitations

The defining feature is consistency: The same expense is recorded every year, making the method straightforward to apply and easy to audit. Businesses can plan cash flow and projections with confidence knowing depreciation expenses remain constant for a given asset.

However, straight-line depreciation assumes an asset loses value at a uniform rate, which may not reflect economic reality for assets like technology or vehicles that depreciate faster early in their life. It also does not account for actual usage; a machine used heavily one year and lightly the next generates the same deduction regardless. Businesses with variable-use assets may find the units-of-production method more accurate.

The method applies only to tangible assets with a determinable useful life. Land is not depreciable. Intangible assets such as patents are amortized rather than depreciated, though straight-line amortization is the standard approach.

Common uses

Straight-line depreciation applies to a wide range of business assets, including:

• Office furniture and fixtures. A $3,000 desk with a seven-year useful life and no salvage value depreciates at $428.57 per year.
• Commercial vehicles. A $40,000 delivery van with a $4,000 salvage value and an eight-year useful life depreciates at $4,500 per year.
• Leasehold improvements. Depreciated over the remaining lease term or the improvement's useful life, whichever is shorter.

Straight-line vs. accelerated depreciation

Accelerated methods such as the double-declining-balance method or MACRS front-load larger deductions in the early years, reducing taxable income more aggressively in the short term and improving near-term cash flow. Straight-line depreciation produces a smoother, more predictable expense pattern that better reflects the actual wear of many assets. The right choice depends on asset type, IRS rules, and the business' tax strategy.

Related terms

• Liquidating distribution: Depreciated book values factor into asset distributions when a business winds down.
• Direct ownership in a business: The ownership structure determines which entity claims depreciation deductions.

FAQs about straight-line depreciation

Is straight-line depreciation accepted under GAAP?

Yes. It is one of the four methods recognized under U.S. GAAP, alongside the declining-balance, units-of-production, and sum-of-years-digits methods.

Can a business switch depreciation methods after it has started depreciating an asset?

Under GAAP, a method change is treated as a change in accounting estimate and applied prospectively. IRS rules are more restrictive and typically require filing Form 3115. Consult a tax professional before making any switch.

Why choose straight-line over an accelerated method?

Accelerated methods improve short-term cash flow but result in smaller deductions and higher taxable income in later years. Businesses that prioritize consistent financial statements or hold assets for their full useful life often find straight-line depreciation simpler and more reflective of actual economic benefit.