For military matters, Working with the Military as an Employer - A Quick Guide:
http://www.acf.hhs.gov/programs/cse/newhire/employer/publication/military_quick_guide.htm

For electronic payments and remittance to State Disbursement Units by Federal agencies:
http://www.acf.hhs.gov/programs/cse/newhire/employer/home.htm

For the Social Security Administration's income withholdings, please refer to OCSE-IM-06-03:
http://www.acf.hhs.gov/programs/cse/pol/IM/2006/im-06-03.htm

For addresses of Federal agencies to send income withholding orders and medical support notices:
http://www.acf.hhs.gov/programs/cse/newhire/employer/home.htm