What Is the Double-Declining Balance Depreciation Method?

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The double declining balance method is an accelerated depreciation method that charges a fixed rate, equal to twice the straight-line rate, against an asset’s declining book value each period. Because the rate stays the same while the base shrinks, the expense is largest in the first year and falls every year after, until the asset’s book value reaches its estimated salvage value.

What depreciation does and where DDB fits

Depreciation spreads the cost of a long-lived asset over the years it helps generate revenue. Under the matching principle in U.S. GAAP, a company that buys equipment it will use for a decade does not expense the full purchase price in year one. It records part of the cost as depreciation expense on the income statement each period and reduces the asset’s carrying amount through accumulated depreciation on the balance sheet.

Straight-line depreciation records the same expense every year. Accelerated methods, including DDB and sum-of-the-years’-digits, front-load the expense. DDB is the most aggressive of the common declining balance variants.

Double declining balance formula

Annual depreciation = 2 × straight-line rate × beginning book value

Where:

• Straight-line rate = 1 ÷ useful life in years (a 10-year asset has a 10% rate, so the DDB rate is 20%)
• Beginning book value = cost minus accumulated depreciation at the start of the period

Two details separate DDB from straight-line. First, salvage value is not subtracted before applying the rate; it acts only as a floor. Second, the base changes every year, so the dollar charge declines even though the percentage does not.

The general declining balance formula replaces the 2 with another factor. A 150% declining balance uses 1.5 times the straight-line rate, and 250% uses 2.5 times. “200% declining balance” and “double declining balance” describe the same method.

Worked example: a 10-year asset

Hypothetical example. A business buys a delivery truck for $30,000, expects to use it for 10 years, and estimates a $3,000 salvage value. Assume full-year depreciation in year one.

Straight-line depreciation would be ($30,000 − $3,000) ÷ 10 = $2,700 per year.

For DDB, the straight-line rate is 10%, so the DDB rate is 20%:

1. Year 1: 20% × $30,000 = $6,000, ending book value $24,000
2. Year 2: 20% × $24,000 = $4,800, ending $19,200
3. Year 3: 20% × $19,200 = $3,840, ending $15,360
4. Year 4: $3,072, ending $12,288
5. Year 5: $2,457.60, ending $9,830.40
6. Year 6: $1,966.08, ending $7,864.32
7. Year 7: $1,572.86, ending $6,291.46
8. Year 8: $1,258.29, ending $5,033.17
9. Years 9 and 10: switch to straight-line, ($5,033.17 − $3,000) ÷ 2 = $1,016.59 per year (rounded), ending at $3,000

In year 1, DDB expenses more than twice the straight-line amount ($6,000 vs. $2,700). By year 6 it records less than straight-line. Both methods depreciate exactly $27,000 in total.

Why the method switches to straight-line

A fixed percentage of a shrinking balance never reaches a set target on its own. Had the truck kept the 20% rate through year 10, the charge would have been $805.31 and the book value would have finished at about $3,221, still above salvage. With a salvage value of zero, pure DDB would leave a small balance forever, which is why the method on its own never takes book value to $0.

Accountants handle this in one of two ways. Some increase the final year’s charge to bring book value down to salvage value. More commonly, they compare the DDB charge each year with straight-line depreciation of the remaining depreciable amount over the remaining life, and switch once straight-line is larger. In the example, that happens in year 9: straight-line gives $1,016.59 while DDB would give $1,006.63.

Can DDB go below salvage value?

No. If a full DDB charge would push book value under salvage value, the charge is limited to the amount that lands exactly on salvage. After that, depreciation stops even if useful life remains.

Why companies use the double declining balance method

DDB fits assets whose usefulness or market value drops fastest when they are new: computers, servers, mobile devices and other technology that newer models make obsolete. Matching a larger expense to the years of highest productivity can give a more faithful picture of the asset’s economic consumption.

The method also shifts reported profit. Higher early depreciation lowers net income and taxable income in the first years and raises them later. Depreciation is a non-cash charge, so it does not change EBITDA, and analysts add it back when computing operating cash flow and free cash flow. Where accelerated depreciation is used for taxes, the deferral of tax payments does improve cash flow in the early years.

DDB and MACRS for U.S. taxes

For U.S. federal income tax, most tangible property placed in service after 1986 is depreciated under MACRS, described in IRS Publication 946. Its general depreciation system uses the 200% declining balance method for 3-, 5-, 7- and 10-year property and 150% for 15- and 20-year property, in each case switching to straight-line when that yields a larger deduction. MACRS differs from book DDB in that salvage value is treated as zero and conventions such as the half-year convention determine first-year depreciation, so the IRS tables do not match a simple DDB schedule.

Limitations

• Lower early earnings. Front-loaded expense makes a newly expanded company look less profitable, which can affect loan covenants, bonuses or valuation multiples tied to net income.
• Estimates drive results. Useful life sets the rate, and salvage value sets the floor. A wrong estimate distorts every year’s charge.
• Comparability. Two companies with identical assets report different profits if one uses straight-line and the other DDB.
• More bookkeeping. The charge must be recalculated each year, the switch point tracked and the salvage floor monitored.
• Poor fit for steady assets. Buildings or equipment that wear evenly are usually better represented by straight-line.

DDB vs. related methods

DDB vs. straight-line. Straight-line charges (cost − salvage) ÷ life every year. DDB charges twice the straight-line rate on the remaining book value, ignores salvage until the floor, and produces a declining expense.

DDB vs. declining balance. Declining balance is the family of methods; the multiplier defines the variant. DDB uses 200%, so it depreciates faster than the 150% version. Some sources call any of these the “reducing balance” method.

DDB vs. sum-of-the-years’-digits. Both are accelerated. Sum-of-the-years’-digits applies a falling fraction to a fixed base (cost minus salvage), so it reaches salvage value exactly without a switch.

Depreciation expense vs. accumulated depreciation. Each year’s DDB charge is the expense. The running total of those charges is accumulated depreciation, and cost minus that total is the book value used as the next year’s base.

The Bottom Line

The method suits businesses that own computers, servers and other technology that loses value fastest when new, and analysts comparing their results. DDB lowers net income and taxable income early and raises them later, while total depreciation matches straight-line. Plan to switch to straight-line near the end of the asset's life and stop at salvage value, and use MACRS rules for U.S. federal taxes instead of a simple DDB schedule.