Can a dna test still be done if a man states he is the father and then wants to make sure he is?

A DNA test can be done at any time. I really don't understand your question.

He already is on record in the courts as being the dad. The baby is in posted care and he is incarcerated.He wants me to get custody, but nobody believes he is the father. Now he wants dna test for future. How can he go about it while he is in prison? Is it going to cost him or me? Is there a legal step to get it done and if proven baby is not his, can he sign off and not be held responsible for the baby?

Let me see if I understand...

He already is on record in the courts as being the dad.

Is he on the birth certificate?


The baby is in posted care

What is "posted care?"


he is incarcerated

Who is incarcerated?


He wants me to get custody,

Why don't YOU have custody? Didn't you give birth to the baby? Why was the baby taken away from you?

Please understand that this is a world wide website, and as such, your location is necessary to provide you with the most accurate information.

He may, ( depending on where you are at, and how long he is either on birth certificate or signed in court to be the father.
Perhaps challenge this in court to get a court ordered DNA test.

And again , why don't you have custody ? Who is the child with now ?

But you merely file for custody, he may have rights to visit the child, or because of long term prison in some areas you may get his rights taken away.

But if you want and do not have custody, file for it in court, his being the father has nothing to do with your ability to file.