Yes it is correct. Any change in your circumstances, such as this windfall, has to be declared.
IVA Procedure: changes in your circumstances � windfalls
The same rules apply to any windfalls you receive during the IVA. A windfall is an unexpected payment, such as an inheritance or a lottery win. If the windfall is of a modest sum, you will be expected to pay half of it to your Supervisor (who will add it to the creditor pot). If however you receive a massive windfall � enough to pay your creditors in full � you would be expected to pay a sum over to the Supervisor that would allow your creditors to get paid their money back in full. Once again, it�s only fair.
As with pay reviews, the windfall rule will be a condition of the IVA � so if you fail to tell your Supervisor about the windfall the IVA can be cancelled.
http://www.debtshredder.co.uk/debt-options-ind ividual-voluntary-arrangement.htm