Should you add your live-in boyfriend or girlfriend to your auto insurance? The simple answer: yes and no.
A long-time client of mine came to me with this question recently. "My boyfriend, who lives with me, is paying a lot more than I am for his car insurance. Can I add him to my policy?" My answer was simple. "Yes, we need to add him as a driver in your household. But, we should not add his car to your policy."
Your auto policy needs to insure the owner of the car. If you are in an accident, an attorney will sue the registered owner and the driver. If we added his car to her policy, there could be a gap in coverage. The insurance company will defend the named insured, which, in this case, is different than the owner of the car. Another reason she shouldn't add his car to her policy is the possibility of him getting into an accident. Her auto policy would increase in premium because his car would be covered under her policy.
Something else to consider is the possibility of a break-up. It could become messy if his car is covered under her insurance, whereas she could easily and quickly remove him as a driver on her policy without leaving him uninsured.
However, she should add him as a driver on her policy. Auto insurance is a contract between you and the insurance company. There is wording in the policy that requires you to add all members of your household as drivers. They may not drive your car, but they still need to be added as drivers. You should also add yourself to your boyfriend's policy as a driver, even if you never drive his car. What happens in an emergency and you need to drive his car for some reason? You could be without coverage.
In summary, add yourselves as drivers on each other's policies but do not combine the two cars onto one policy unless you get married and start to incorporate other aspects of your life legally.