Self Assessment Accountants fees

My accountant prepares and submits my self assessment which includes property income. I tried to claim the full amount of the accountants fees against my tax return as a business expense but my accountant says HMRC only allow a percentage of the fees to be claimed as an expense. Is this the case and is there a formula for working this out?

Hi ,
 

You cannot claim for your accountant preparing and submitting your tax return.  This is not a business expense.  You can claim business expenses for retaining an accountant managing your business finances and books etc. Thank you .