Compare four depreciation patterns

Hold the inputs constant

Compare methods only after aligning cost, salvage value, useful life, readiness date, and period convention. Straight-line assigns an equal amount by time. The activity method assigns cost from supported units of service. Declining balance applies a fixed rate to a falling carrying amount. Sum-of-the-years' digits applies falling fractions to a fixed depreciable amount.

Straight-line and activity can move expense in different periods when output is uneven. The two accelerated methods usually assign more expense early, but they use different bases. Declining balance treats salvage as a floor. The years'-digits method removes salvage before applying its fractions.

Match the pattern to evidence

The general rule calls for a systematic and rational pattern. See ASC 360-10-35-4. Paragraph 35-7 identifies declining balance as one qualifying method when early productivity or revenue capacity is greater. The guidance does not make acceleration a default.

A schedule proves its arithmetic. It does not prove that machine hours measure service, that early capacity is greater, or that an equal time pattern fits. Retain the operational evidence used to choose the pattern.

Exit check

Compute all four methods from one controlled input set. Reconcile each schedule to the same total depreciable amount, then state which service evidence would support each pattern.