Once you have the completion certificate you are not bound by the windfall terms. If you have made your last payment and not received this certificate you may well be bound.
If the windfall occurred during the IVA ( prior to the date of the completion certificate) it is always due to the IVA, even if it comes to light some time later. Anything after that date is outside the reach of the arrangement.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014
I don't think it is that clear cut and certainly could be tested in court. I think the contract could easily be judged "unfair" if there is an open ended commitment.
Certainly in my proposal the term of the IVA is referenced at least twice as being 72 months.
As Michael says after completion certificate but sometimes this can take months/years to issue so therefore it's not always fair on other who receive theirs only weeks after completion.
I think Mole has a valid point although untested.
IVA final payment left the bank on the 26th January 2013...looking forward to a debt free future.