As stated in the instructions for the Form 433-D, Installment Agreement - https://www.irs.gov/pub/irs-pdf/f433d.pdf
Review the terms of this agreement. When you’ve completed this agreement form, please sign and date it. Then, return Part 1 to IRS at the address on the letter that came with it or the address shown in the “For assistance” box on the front of the form.
