You can apply for a business bank account at any time. If the account is for a limited company and you do not want an overdraft or other credit facilities, then it should be relatively simple to get the account open. If you need a sole trader account, then in effect the account would be in your name. Given your IVA started in Sept 03, the history of you having had an IVA will remain on your credit file for a further 3 months until Sept 09. However, if you explain to the bank that you are now debt free and expecially if you do not want to borrow any money, you should be able to open an account with little problem.