I have a 4 yr old boy who's father has never met him. This past yr he has started to pay child support but continuosly moves so is very hard to find. I have sole custody and placement of my son. Do I need his permission to change the name?

Yep, biodad must agree. Legally he still has rights.

But he does not have custody or placement. He wants my husband to adopt him because he doesn't want to pay child support. So if he does not agree, then a judge will deny it? That's bull.

but he does not have custody or placement. He wants my husband to adopt him because he doesn't wanna pay child support. So if he does not agree, then a judge will deny it? Thats bull.

No its not bull. And if you have been married long enough then why not have your husband adopt the child. Then while making the adoption formal you can get a name change done.

A birth certificate is a legal document, you can't change what's on the birth certificate without a court order. You bring a petition to change his name and the court will ask what about the father. If the father fights it he will win. That's the law.

However, if he's willing to approve an adoption, then go that route.