Hi.You can claim capital allowances on the cost either over a period of several tax years under the writing down allowance rules at 18% per annum on a reducing balance or in one year under the annual investment allowance rules. You should disallow a percentage of your claim to reflect any private usage of the computer. Given the relatively low cost, it would be simplest to write off the total cost against the year of purchase. Read about capital allowances here.I hope this helps but let me know if you have any further questions.
Does this mean that I can put down say £500 (as the total cost being £800 and I do use the computer for a small amount of personal use) down as a capital allowance for this year?