To be allowed to become joint owner by the mortgage company I believe you would have to prove that you had sufficient income, as you would then be solely liable for the mortgage should anything happen to your boyfriend, or should he lose his job. I think you may get some answers from people more knowledgeable than me. I can only tell you as I understand it to be. This is why people take out mortgage protection insurance in case of their death to protect their wife/partner, and children. I think it is quite expensive. Sorry I can't be of more help.