It depends on what the attachment relates to. If it is recovery of a debt included in the IVA,then no, it is not allowed. Speak to your IP to sort it out.
If it is recovery of a new debt, then, yes it is allowed and also could see the IVA failed for taking on new credit.
If recovery of something like overpaid benefits, unpaid maintenance or other court ordered payment or recovery of a fine, it would depend on the exact reasons.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014