I am retired and recieve military disability, disability social security and a pension from the USPS.

You have several issues that might benefit from an attorney's guidance: Is the child your son?  You can request a test to determine paternity.  The papers you received should tell you how to respond to that issue, but an attorney can make it more clear.  The papers you received sound like they were from a support action started in your county court.  A court deciding support will take into account all of your sources of income in calculating your child support responsibility.  If he is your son, and you notify Social Security, then he may be eligible for what are called "derivative benefits", which are payments to him on your behalf.  I do not know if the military has a similar benefit, but if they do you could reduce your out of pocket payments in support. I suggest you talk with an attorney just because you have these different sources of income and there may be issues with each of them.  Your case is just more complicated than most.