An accountant needs to calculate depreciation on a $55,000 vehicle that has a 5-year useful life and $8,000 salvage value, using three different methods to advise their client on which produces the best tax outcome in the early years.
Depreciation Calculator
Tax
Expected value at end of life
Straight-line: (Cost − Salvage) ÷ Useful life
Declining balance: Book value × Depreciation rate%
SYD: Remaining life ÷ Sum of years digits × (Cost − Salvage)
Straight-line gives equal deductions each year. Declining balance front-loads deductions — better for tax in early years. Always confirm with your accountant or the ATO.
Reference: Finance Formulas Cheatsheet — Section 7 Depreciation Methods · ATO.gov.au — Depreciation
Results are estimates for planning purposes. Verify with current standards and a qualified professional.
1 What this calculator does
Calculates annual depreciation using three methods: straight-line (equal annual amounts), declining balance (fixed percentage of book value), and sum-of-years-digits (front-loaded acceleration). Shows Year 1, Year 2 and Year 3 depreciation amounts and book value after Year 1.
2 Formula & professional reasoning
Straight-line: Annual depreciation = (Cost - Salvage) / Useful life
Declining balance: Year t depreciation = Book value at start of year x Rate%
Book value reduces each year as depreciation is applied
Sum-of-years-digits: Year t = (Remaining life / Sum of years) x (Cost - Salvage)
Sum of years = n(n+1)/2 where n = useful life
Straight-line depreciation is the simplest -- equal amounts each year. Declining balance front-loads depreciation, recognising that assets lose more value in early years (a new car loses 15-20% in year 1 vs much less in year 8). Sum-of-years-digits is another accelerating method -- mathematically derived to front-load without requiring a specified percentage rate. For tax purposes in Australia (Div 43 building allowance, Div 40 plant and equipment), the ATO has specific effective lives and methods -- this calculator is for financial reporting purposes.
3 Worked examples
⚠️ Illustrative example only — not clinical or professional instruction.
Basic
Vehicle -- straight-line depreciation
Given: Cost: $55,000 | Salvage: $8,000 | Life: 5 years | Method: straight-line
Working:
Depreciable amount: $55,000 - $8,000 = $47,000 | Annual: $47,000 / 5 = $9,400/yr | Book value after yr 1: $55,000 - $9,400 = $45,600Answer: Annual depreciation: $9,400/yr for 5 years | Book value end yr 1: $45,600
💡 Straight-line is simple and consistent. Total depreciation over 5 years: $47,000. Final book value equals salvage value of $8,000.
Standard
Same vehicle -- declining balance at 30%
Given: Cost: $55,000 | Salvage: $8,000 | Life: 5 years | Method: declining balance 30%
Working:
Year 1: $55,000 x 0.30 = $16,500 | Book value: $38,500 | Year 2: $38,500 x 0.30 = $11,550 | Book value: $26,950 | Year 3: $26,950 x 0.30 = $8,085Answer: Year 1: $16,500 | Year 2: $11,550 | Year 3: $8,085 | Front-loaded depreciation
💡 Declining balance generates $16,500 in year 1 vs $9,400 straight-line -- $7,100 more in the first year. For tax purposes this accelerates the deduction into early years where the business may need it most.
Advanced
Sum-of-years-digits comparison
Given: Cost: $55,000 | Salvage: $8,000 | Life: 5 years | Method: SYD
Working:
Sum = 5(5+1)/2 = 15 | Year 1: (5/15) x $47,000 = $15,667 | Year 2: (4/15) x $47,000 = $12,533 | Year 3: (3/15) x $47,000 = $9,400Answer: Year 1: $15,667 | Year 2: $12,533 | Year 3: $9,400 | SL equivalent at year 3
💡 SYD produces $15,667 in year 1 -- between straight-line ($9,400) and 30% declining balance ($16,500). SYD always fully depreciates to salvage value over the exact useful life, which declining balance at a fixed rate may not achieve.
4 Sanity check
Method comparison at year 1 for same asset
Straight-line: lowest year 1 deduction | SYD: middle | Declining balance: highest year 1 deduction
ATO effective life rates (2024 approx)
Motor vehicles: 8 years effective life (150% DB available) | Office equipment: 5 years | Manufacturing equipment: varies | Buildings: Div 43 2.5% p.a.
ATO rates are for tax depreciation -- financial reporting may use different useful lives.
Declining balance: book value may exceed salvage value at end of life
Fixed-rate declining balance may not reach salvage value exactly at end of life -- switch to straight-line in final years
Tax vs accounting depreciation
Companies often use different methods for tax (accelerated, ATO rates) vs financial reporting (AASB 116 property, plant and equipment)
5 Common errors
| Error | Cause | Consequence | Fix |
|---|---|---|---|
| Using the same depreciation for tax and financial reporting without checking ATO requirements | Assuming one method works for both purposes | Either overstating or understating the tax deduction | AASB 116 non-compliance | Financial reporting depreciation follows AASB 116 (using expected useful life and pattern of consumption). Tax depreciation follows ATO effective life tables (Div 40 for plant and equipment). They are separate calculations. |
| Not including a salvage value in straight-line calculations | Depreciating to zero when an asset will have residual value | Depreciation overstated in the books | Asset book value falls below actual residual value | Straight-line depreciable amount = Cost minus salvage value. Do not depreciate an asset below its estimated salvage value. |
| Using declining balance at an arbitrary rate without reference to ATO effective life | Choosing 30% or 20% without a basis | Depreciation rate not supportable for tax purposes | For tax purposes, use the ATO's prescribed effective life or the Commissioner's determination. The diminishing value rate = 200% / effective life years. |
| Not writing off an asset when it is disposed of or written down | Leaving assets on the books after disposal or damage | Assets overstated on the balance sheet | Depreciation charged on assets no longer owned | When an asset is sold, scrapped or written off, remove both the cost and accumulated depreciation from the books and recognise any gain or loss on disposal. |
6 Reference & regulatory links
🇦🇺 Australia
7 Professional workflow
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