I bought a basic laptop and special software for [self-employed] work. Do I write this cost off as a capital allowance (12.5% per yr - but it won't last 8 yrs!) or as a once-off expense? Many thanks.
accounting = depreciate it over 3 years
capital allowance -- claim 12.5 % per year over 8 years --if it packs in claim the balance in the year of its demise
So you would have timing differences in your return.
You would need to adjust your profit at the end of the year
Add back your accounting depreciation to your profit and deduct the Capital allowance for the year