I live in Connecticut and have a 2 1/2 year old daughter. Her biological father has not had any contact with her since she was 5 months old. My husband has raised her since she was about 6 months old he is all she knows as her "daddy". In the fall she is starting preschool. I wanted to see if I could file for abandonment as her biological has no relationship with her and terminate his rights? My husband wants to adopt her and give her his name prior to her starting school in the fall. Is this possible?

Is the bio father on the birth certificate? Is he on child support? Is there a visitation order?

It is a good idea to browse around a site like this before posting. Had you done so, you might have found this sticky:
https://www.askmehelpdesk.com/family-law/child-abandonment-read-first-364259.html which would have, at least partially answered your question.

No you can't file for abandonment because abandonment is not something you can charge someone with in most places. Abandonment may be used a means, but not an end. The thing is you HAVE an end and that is your husband adopting your daughter. That's what you need to go for and concentrate on.

The problem is despite the father's lack of contact, you will still need his permission for the adoption or make an effort to get it. This is where the abandonment comes in. If you do not know how to contact him, the lack of contact may work in your favor to get a court to approve the adoption without his permission.

The bottom line here is you need an attorney to prepare the adoption permission. The attorney will walk you through what you need to do and prepare the paperwork. So you NEED to find an attorney now and start the process.

If you want to file to allow your new partner to adopt, then you contact the bio father and see if he will sign over his rights to allow him to adopt