Reducing balance depreciation .....

I'm currently working on a client with a financial period end of 15 months, as compared to 12 months. However, I have ran into some difficulty with the fixed assets and calculating the depreciation.<BR><BR>At my workplace, we calculate depreciation on a yearly basis, rather than monthly.. eg: we charge a full year of deprecation in the year of acquisition but none in the year of disposal.<BR><BR>Lets say the opening net book value of an asset is £2,500. The financial year runs for 15 months (let's say from 1 January 2003 to 31 March 2004, for simplicity) instead of 12. The annual rate of depreciation is 25%. <BR><BR>Would you simply take 25% to cover from 1 Jan to 31 Dec 2003, then calculate a further 25% - which would take you upto 31 Dec 2004 - but only take a quarter of that amount of deprecation as the remaining amount falls outwith our year end.<BR><BR>This will proberly be wrong but I am only taking a rough guess. Any help is appreciated