GSOE9830 Chap.5 Depreciation Methods and Tax Timing

Depreciation Methods and Tax Timing

Depreciation allocates depreciable asset basis across time and affects cash flow through tax relief. Straight line spreads the basis evenly, while declining balance creates larger deductions early and smaller deductions later. Other methods can follow production or switch between patterns.

The total depreciable amount remains bounded by cost and residual value, but the timing of deductions changes the present value of the tax shield. A reliable schedule carries opening book value through depreciation to closing book value in every year and never crosses the stated residual boundary. Declining balance applies its rate to the current opening balance, not repeatedly to original cost.

A switch method compares allowable deductions on the remaining basis rather than changing at a memorised date. Parallel schedules should first reconcile the same lifetime basis, then compare discounted tax relief so the difference reflects timing alone.

What this chapter covers

• 01

  Depreciable basis

• 02

  Straight line

• 03

  Declining balance

• 04

  Book value

• 05

  Residual value

• 06

  Tax-shield timing

Worked example · free

Build a straight-line depreciation and tax-relief schedule

Key terms

Depreciable basis

Asset cost available for depreciation after the residual-value adjustment.

Straight line

A method that allocates equal depreciation in each period.

Declining balance

A method applying a fixed rate to opening book value.

Book value

Original cost less accumulated depreciation at a stated date.

Depreciation Methods and Tax Timing FAQ

Exam move

Begin every depreciation problem with the depreciable basis, method, life, residual value and tax rate written in separate cells. Do not calculate until the basis boundary is clear. For straight line, subtract residual value from cost and divide by the depreciable life. Copy the deduction across the permitted years, then verify that cumulative depreciation plus closing book value equals original cost.

The final closing value must equal the stated residual rather than pass below it. For declining balance, create opening book value, rate, depreciation and closing book value rows. Each year applies the percentage to that year’s opening value, not to original cost. Carry the closing value into the next period and cap the final deduction when the mechanical percentage would breach the residual boundary.

This running ledger prevents a shrinking deduction from being mistaken for a constant amount. When a switch method is supplied, compute both the declining-balance deduction and straight-line deduction on remaining depreciable book value at the decision date. Use the permitted larger amount and explain the switch.

Do not switch merely because a pre-memorised year has arrived; the remaining life and basis determine the comparison. Keep units-of-production work tied to actual output. Calculate a depreciable amount per unit and multiply by each period’s production, while still respecting the total basis limit. Separate depreciation from cash. The asset purchase appears as capital expenditure when paid.

Depreciation enters taxable income, and the resulting tax reduction affects after-tax cash flow. Create a tax-relief row equal to depreciation multiplied by the rate, then discount those relief amounts when comparing methods. Two schedules can provide the same lifetime deduction yet different present values because the timing differs. Practise a parallel comparison using one asset under straight line and declining balance.

Reconcile each schedule independently before comparing the tax shields. Calculate the undiscounted relief total as a basis check, then calculate present value to measure the advantage of earlier deductions. If totals differ unexpectedly, look for residual treatment or an over-depreciated final year before interpreting timing.

Maintain an error log for residual omitted, original cost reused under declining balance, opening and closing values reversed, depreciation treated as cash, tax relief given the wrong sign and final book value below the boundary. For each mistake, write the ledger identity that catches it. Before the test, reconstruct a four-year schedule without notes and explain every row aloud.

Finish with a sentence that distinguishes allocation from payment and total deduction from timing value. That distinction is the centre of the chapter and protects the later after-tax NPV calculation.

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