Depreciation Calculator Australia
Depreciation calculator Australia: work out the first-year tax deduction for an asset using the prime cost or diminishing value method.

What it does
The Depreciation Calculator works out the first-year tax deduction for an asset using either the prime cost (straight-line) or diminishing value method.
Data sources & parameters
This calculator uses standard financial formulas and runs entirely in your browser. It needs no external rate data — your result is computed only from the values you enter above.
We always strive to use the latest data for every variable so our results and reports are as accurate as possible. Even so, errors are possible — you should not rely on this tool or its report alone, and we accept no liability for any decision made based on it.
The formula
Prime cost = value ÷ life; diminishing value (year 1) = value × (2 ÷ life)
How it works
Prime cost spreads the cost evenly over the effective life. Diminishing value applies a rate of 200% ÷ effective life to the remaining value, so year one is larger.
Where it is used
- Claiming depreciation on business or rental assets
- Comparing the two depreciation methods
- Estimating first-year deductions
Worked example
A A$20,000.00 asset over a 5-year life gives a first-year deduction of … under diminishing value (vs … prime cost), leaving ….
If you own assets that help produce income, whether for a business or a rental property, you can usually claim their decline in value as a tax deduction over time. This depreciation calculator for Australia works out the first-year deduction for an asset using either the prime cost method or the diminishing value method, so you can see how much you can claim and how the two approaches compare.
What depreciation means for tax
Most assets used to earn income do not give you a single, upfront deduction for their full cost. Instead, you claim their decline in value gradually, over what is known as the asset's effective life. This spreads the deduction across the years the asset is helping you produce income, matching the deduction to the use of the asset.
Depreciation applies to eligible assets such as equipment, fixtures and fittings used in a business or an income-producing property. The calculator focuses on the first-year deduction, which is the figure people most often want when they buy something new.
The two methods explained
Australia recognises two main ways to calculate depreciation, and they produce very different patterns of deduction:
- Prime cost (straight-line). The deduction is spread evenly across the asset's effective life. You claim a similar amount each year until the asset is fully written off.
- Diminishing value. The deduction is larger in the early years and smaller later, because the rate is applied to the asset's reducing balance rather than its original cost.
Both methods write off the asset over time; they simply differ in when the deductions fall. The calculator lets you compare the first-year result under each so you can see the contrast clearly.
Prime cost versus diminishing value
Choosing between the methods is a planning decision:
- Diminishing value front-loads your deductions. If you want a larger claim sooner, perhaps because you expect higher income in the early years, this method brings more of the benefit forward.
- Prime cost gives a steady, predictable deduction. If you prefer even claims across the asset's life, or want a smoother tax position year to year, this suits better.
An important point: once you choose a method for a particular asset, you generally cannot switch it later. So it is worth thinking about your longer-term position before you decide, not just the first-year number.
The role of effective life
Both methods depend on the asset's effective life, meaning how long it is expected to be used to produce income. Effective life drives the depreciation rate:
- A shorter effective life means a faster write-off and larger yearly deductions.
- A longer effective life means a slower write-off spread over more years.
Getting the effective life right matters, because it shapes every year's deduction. The calculator uses the effective life you enter, so an accurate figure gives an accurate result.
What you need to enter
To estimate your first-year deduction, have these ready:
- Asset cost: what you paid for the asset
- Effective life: the expected years of income-producing use
- Method: prime cost or diminishing value
The tool then returns the first-year deduction under your chosen method, which you can compare against the alternative.
Immediate deductions and concessions
Not every asset has to be depreciated over years. Certain low-cost assets and specific concessions can allow an immediate deduction in the year you buy them, subject to the current rules and thresholds. These provisions change over time, so it is worth checking whether your asset qualifies before you commit to depreciating it gradually. If it does, you may be able to claim the whole amount at once instead.
Using the estimate
Depreciation is one of the more valuable, and more overlooked, deductions available to businesses and property investors. Running the numbers before and after a purchase helps you understand the after-tax cost of an asset and plan your deductions across the years ahead.
Treat the result as a planning figure. Depreciation rules, effective life determinations and available concessions are detailed and can change, so confirm the specifics for your situation with a registered tax professional before you lodge.
Keeping good records
Depreciation claims rely on solid records, and the time to build them is when you acquire the asset, not at tax time. Useful things to keep include:
- The purchase invoice, showing the cost and the date
- A note of the effective life you have adopted and why
- The method you chose for each asset, since it generally cannot be changed later
- A running schedule of the written-down value from year to year
A depreciation schedule that carries forward each year saves considerable effort and reduces the risk of errors. For property investors in particular, a professionally prepared schedule can identify claimable items that are easy to miss.
Depreciation is a genuine, ongoing deduction that rewards planning and good records. This calculator gives you a clear first-year figure under either method, which is the natural starting point for deciding how to treat a new asset and what it really costs you after tax. Before you buy a significant asset, it is worth modelling the deduction under both prime cost and diminishing value, so you understand the after-tax cost and can match the timing of your deductions to your expected income. Because the method you choose usually cannot be changed later, a few minutes with the calculator at the outset can shape your position for years to come.
This article is general information only and not financial or tax advice; confirm your position with a registered tax professional.
About This Tool: Depreciation Calculator Australia
Depreciation calculator Australia: use this tool to get an instant estimate based on the figures you enter. Adjust the inputs above to match your situation, or browse all our calculators to plan your next step.
