I have full custody, I am the only one listed on the birth certificate. My son is 4 months old. Can I deny a paternity test? And would it cost him much money to get a court order for one?

You can't deny him one if he demands it...

What is your objection to the child having a father? Sure you can deny the test but you will be forced to sit in jail until you agree. Its not about you it is about the child.

YOU can deny a paternity test if HE requests one. But you can't defy a court order if he obtains one. And he can easily obtain one. It wouldn't be expensive. That's the legal answer.

But Califdad makes a valid point. You need to consider your child, not your feelings.