I am assuming that you are being asked to claim something (refund, benefits ?? ) and they have taken a stab at the amount payable to the IVA in the event that the claim is successful --- but that amount, being a guess is not 'carved in stone' and might not even happen if the claim is refused.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014 http://foggy.blogs.iva.co.uk