Welcome to the forum. Your IP will have to provide you with specific case advice as it depends on how your iva proposal was written.
If you were entitled to this to go towards your rent it maybe classed as income and therefore some or all maybe due on your iva.
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If there was an allowance on your I&E for the full rent I would think this may be deemed a windfall and you also need to review your I&E going forward. Check with your own firm as they may have a different opinion.