During your IVA your IP will be checking your income and expenditure, usually on a yearly basis. They will have payslips and P60's and some require bank statements.
Once you have made your final payment, as far as I am aware, within a short space of time you will receive a certificate of completion.
Sharing from experiences of dealing with debt
The greatness of a man is not in how much wealth he acquires, but in his integrity and his ability to affect those around him positively.
Bob Marley. http://kallis3.blogs.iva.co.uk