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GlossaryFinance

What is sum-of-years' digits?

Abbreviated as SYD. Also known as: SYD, sum of the years digits, SOYD.

Definition

Sum-of-years’ digits (SYD) is an accelerated method that multiplies the depreciable base by a shrinking fraction: remaining life ÷ sum of the years.

1 min readFinanceExplore Asetavo depreciation →

Sum-of-years' digits front-loads depreciation, but less steeply than double-declining balance. Add up the digits of the useful life — for 5 years, 5 + 4 + 3 + 2 + 1 = 15 (or use n(n + 1) ÷ 2). Each year's charge is the depreciable base multiplied by the remaining life at the start of that year over that sum.

Worked example

Cost $30,000, salvage $5,000, life 5 years → depreciable base $25,000.

YearFractionDepreciationClosing NBV
15/15$8,333.33$21,666.67
24/15$6,666.67$15,000.00
33/15$5,000.00$10,000.00
42/15$3,333.33$6,666.67
51/15$1,666.67$5,000.00
Total = $25,000, landing exactly on salvage value.

Why use it

SYD gives a smooth, declining charge that reaches salvage exactly — no caps or switches needed — which makes it a tidy choice for assets that are most productive early in life.

Try the numbers yourself in our free depreciation calculator.

In Asetavo

SYD is one of Asetavo's eight methods for book or tax profiles.

In practice

Want to understand this in practice?

GuideFixed asset depreciation explainedMethods, schedules, book vs tax and worked examples — in plain English.Read the guide →
Related features
Depreciation
Related terms
Double-declining balanceDouble-declining balance (DDB) is declining balance at twice the straight-line rate — e.g. 40% a year for a 5-year asset — heavily front-loading depreciation.DepreciationDepreciation spreads the cost of a fixed asset over its useful life, recording part of the cost as an expense each period as the asset is used up.Straight-line depreciationStraight-line depreciation charges the same amount each period: (cost − salvage value) ÷ useful life. It is the simplest and most common book method.Declining balance depreciationDeclining (reducing) balance depreciation charges a fixed percentage of an asset’s remaining book value each year, so charges start high and fall.
From definition to done

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