Federal Taxes: Form 4669

I had two rental houses a few years back, which have since been sold, and just recently the local Housing Authority (I rented Section 8) sent me this form saying it needs to be signed and returned immediately. I don't see anything the compels me to sign this form. All income was properly accounted for etc so I don't see the point. Can someone explain to me the point of this form?

Thank you

Federal Taxes: Form 4669