What is IRS Form 433-A used for?

Form 433-A is a detailed Collection Information Statement used by Field Collection officers for individual taxpayers. It documents income, expenses, assets, and debts.
Automated Collection Service (also called Campus Collections, or ACS) utilizes Forms 433-F and 433-H. The reason for this is that the line items matches their input screen. If dealing with ACS tax pros should try and utilize the same form to make providing the information to the ACS employee easy.