• ### The diminishing value method Warning:

This information may not apply to the current year. Check the content carefully to ensure it is applicable to your circumstances.

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The diminishing value method assumes that the decline in value each year is a constant proportion of the remaining value and produces a progressively smaller decline over time. For depreciating assets that you started to hold on or after 10 May 2006 the formula for the decline in value is:

Base value × (days held [see Note] ÷ 365) × (200% ÷ asset's effective life)

Note: can be 366 in a leap year

where the base value for the income year in which an asset's start time occurs is the asset's cost. For a later income year, the base value is the asset's opening adjustable value for that year plus any amounts included in the asset's second element of cost for that year.

Generally, you can use this formula to work out the decline in value of an eligible depreciating asset if you started to hold it on or after 10 May 2006. However, this formula may not apply in some cases – for example, if you held an asset before 10 May 2006 but then disposed of it and reacquired it on or after 10 May 2006 just so that you could use this formula to work out the asset's decline in value.

For depreciating assets you started to hold prior to 10 May 2006 the formula for the decline in value is:

Base value × (days held [see Note] ÷ 365) × (150% ÷ asset's effective life)

Note: can be 366 in a leap year

Example: Base value – ignoring any GST impact

Leo purchased a computer for \$6,000. The computer's base value in its start year would be its cost of \$6,000. If the computer's decline in value for that year is \$1,500 and no amounts are included in the second element of the computer's cost, its base value for the next income year would be its opening adjustable value of \$4,500. This amount is the cost of the computer of \$6,000 less its decline in value of \$1,500.

'Days held' is the number of days you held the asset in the income year on which you used it or had it installed ready for use for any purpose. If the income year is the one in which the asset's start time occurs, you work out the days held from its start time. If a balancing adjustment event occurs for the asset during the income year (for example, if you sell it), you work out the days held up until the day the balancing adjustment event occurred – see What happens if you no longer hold or use a depreciating asset? for information about balancing adjustment events.

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Example: Diminishing value method – ignoring any GST impact

Laura purchased a photocopier on 1 July 2007 for \$1,500. The asset started to be used on the day of its purchase and has an effective life of five years. Laura chose to use the diminishing value method to work out the decline in value of the photocopier. The decline in value for the 2007–08 income year would be \$601. This is worked out as follows:

\$1,500 × (366 ÷ 365) × (200% ÷ 5)

If Laura used the photocopier wholly for taxable purposes in that income year, she would be entitled to a deduction equal to the decline in value. The adjustable value of the asset at 30 June 2008 would be \$899. This is the cost of the asset (\$1,500) less its decline in value up to that time (\$601).

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