My boyfriend is still married not able to afford a divorce at this time but his wife is pregnant with her boyfriends child and now internal revenue is saying he is liable for this child because they are married? And they are telling us that her boyfriend can't sign the birthcertificate because she is married so she would either have to let her husband sign or put father unknown until paternity is set up we live in Florida they say it is Florida law is this the facts?

I don't know what Internal Revenue has to do with it, but they are right, legally, he is responsible for the child. It doesn't matter who the father is. I hope she does the right thing and lets her husband sign to give the baby a proper name.

Tick

If you put what you know is a lie on a birth certificate you are committing a crime.

What does IRS have to do with this? IRS collects taxes. It doesn't dictate paternity OR Florida Law.

Put the father's name on the birth certificate.

A man would stand up and claim his child.

Some states view the husband as the father unless it is contested.
DNA May help.

Interestingly I found a case in which a husband was found to be the father of the child and FORCED to pay child support. FindLaw's Writ - Grossman: Paternity Misrepresentation A Florida Court Rules That a Husband Waited Too Long to Disprove Fatherhood, and Reaffirms His Status as the Child's Father

All of you - you dating a married man, the married man's wife claiming the child is not his - need to consult with an Attorney or you could deal with this situation until the child is 21 years old in a manner which is NOT your choice.

He can pay now (for an Attorney) or pay the painful way for the rest of his life.