Pro-Rata Refund Calculator
Use this app to quickly calculate a pro-rated refund if the service start date, end date, next billing date, and amount paid are known. This app is useful in determining pro-rated refunds for cancelled or migrated/upgraded services.
Had to do 90 pro-rated refunds, app was very useful. Would be nice if there was a "clear form" button, that's the only thing that I think could constitute an improvement.