Yes -- if you use the arguement that it was before the IVA it should be declared as an asset and, possibly, surrendered as such to creditors. If you go by when you get the money, i.e. post IVA it would be due as an after acquired asset.
If you do not declare it at all, it could come out of the woodwork later and become an issue -- so a bit of a gamble.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014