Q: I have lived with the same person for nearly 20 years, but we have never married. We have joint bank accounts with our names and business name on them. I have always used my maiden name and consider myself unmarried, and we both file our taxes and other legal documents as single people. My family is concerned that my partner may have legal rights in property I inherit.
A: The fact that you have lived with someone, even for 20 years, does not give him any interest in your property. Idaho used to have common law marriage, but that was eliminated by statute effective January 1, 1996.
Since you began your relationship before that date, it could be argued that marriage was created under common law before the law was changed, and if so, would not have been affected by the termination of common law marriage. However, it does not appear that the relationship would have ever qualified for common law marriage since the essential for common law marriage is consent and consent is shown by “holding yourself out as married.” It does not appear from your question that you ever did so. Even if there were a common law marriage, your inheritance would still be your separate property as opposed to community property unless you mixed it with your joint property.
Even though it appears you are not married, there is always the risk that claim could be asserted. Therefore, a written acknowledgment by your partner that you are not married would be prudent. All he would have to do is sign a simple statement (preferably before a notary) that you never have held yourselves out as husband and wife and are not married.
Once you own the property, you have the power to do whatever you want with it, including giving it to your partner or bequeathing it to him in your will. To avoid the possibility of this happening, your family could leave the property in a trust for your benefit. The assets would be available for your use on a need basis, but you would not have the power to pass them outside the family. At your death, the trust would direct where the property would be distributed.