Resolved Question: Can I add my girlfriend to my health insurance if we live together?

There are several levels to this "domestic partner" benefit. First, state law has to allow it. Then, the insurance carrier has to allow it. Lastly, your company has to allow it. It has nothing to do with "common law", but all will require that you meet certain criteria. It also has nothing to do with same-sex marriage or civil unions.

The easiest place to get an answer to this question is the Human Resources department of your company. They will know if the state, the insurance company, and they allow it. You may have to wait until open enrollment in order to add her to your insurance, if allowed, unless some qualifying event happened, like she lost prior coverage. You will have to provide proof of that prior coverage.