Income & Expenditure Form

I have made a Drupal site for a debt management company where they can store there client data. They need to fill out an income and expenditure form for each client they have which at the moment they do on excel and attach it to the content type "Client" what i would like to do is have this built into the Drupal site. As there is alot of different fields i was wondering what the best solution for this is. Also once the fields have been filled in it need to calculate there disposable income. I have attached a copy of the form they are currently using, any help is greatly appreciated.