Hello Roy, I am Keith, one of the experts on Just Answer, and happy to help you with your question.
I am sorry, an IVA is merely a means of settling a personal debt and not normally deductible for either Income nor Corporation Tax purposes. However, if the IVA is recovering business expenses which have yet to be passed through your books of account then they can be used to offset tax in the current accounting period in the normal manner.
The IVA payment does not form part of your mothly allowance for spending.
Your accountant's advice is sound.
You might find some of the payments allowable; that I cannot verify without full detail.
I do hope my response has been of some assistance and not rained overmuch on your parade..
Thank you for your excellent support.