Hi Dave,
Hope you don't mind me jumping in here but being an accountant I thought I would explain the rules of depreciation.
Basically depreciation is a way of spreading the cost of an asset over its useful life. The 2 most common methods of depreciation you can use are the straight line method or the reducing balance method.
Straight Line Method
This method is probably the most common one. What this method does is charge equal annual amounts of depreciation over the course of the asset's life until it reaches zero value or its scrap value (the technical term here in th UK for scrap value is residual value)
The formula is: (Cost of asset - residual value) / Useful Life
For example if you purchase an asset for £10,000 and you estimate its residual value and useful life to be £500 and 5 years, then the annual depreciation charge would be:
(£10,000-£500) / 5 = £1,900 p.a.
Reducing Balance Method
This method calculates depreciation as a % of the asset's net book value (NBV). The NBV is the cost of the asset less depreciation to date. Using this method means that highest amount of depreciation is charged in the first year of the asset's life. For example, again if you purchase an asset for £10,000 and has a residual value of £500 and the depreciation rate is 20% then the depreciation would be:
Year 1 (10,000-500) x 20% = 1,900
NBV = £7,600
Year 2 = 7,600 x 20% = 1,520
NBV = £6,080
Year 3 = 6,080 x 20% = 1,216
NBV = £4,864
Year 4 = 4,864 x 20% = 972.80
NBV = £3,891.20
Year 5 = 3891.20 x 20% = 778.24
NBV = 3,112.96
etc.
As you can see the depreciation charge is reduced each year and will carry on depreciating until you either write it off or the residual value is reached.
Hopefully I've explained it enough to give you an understanding of how the calculations work.
HTH
Rob
p.s. Apologies to Stacy who started this thread for going slightly off topic
