Hi jane r and welcome to the forum - apoligies for the tardy reply.
Your customer ought to have no difficulty in setting up a business whilst he is in an IVA, but the business will need to provide him with sufficient income to be able to maintain his usual IVA payments. He will also need to advise his supervisor of his changed status and provide copies of his trading accounts to the supervisor each year to ensure that he is paying over all his disposable income.
He ought to contact an insolvency practitioner directly to seek more specific advice.
Hope this helps.
Regards, Melanie Giles, Insolvency Practitioner for over 20 years.
For further details contact me at
http://www.melaniegiles.com and view my IVA blog at:
http://melaniegiles.blogs.iva.co.uk