How do I chase the father of my son for child support?

You have several options, depending on facts you do not mention.  Is dad on the birth certificate, or has paternity been established by any court?  If no to both, then paternity is the first thing to establish, and then support (it can be done, usually, in the same proceedings).  You don't say WHERE in the U.S. dad is living -- you need to proceed, either through private counsel, or through the District Attorney ("D.A."), of the State where dad is.  I suggest you review some background information at the below links, and then call either a D.A. or hire a private family law specialist to begin the matter.  You shouldn't wait -- there are statutes of limitation that cut off your right, at least to some past sums, after too much time elapses. http://willicklawgroup.com/paternity/ http://willicklawgroup.com/child-support/