If you decide to do joint account, approach this as a business transaction and put protections in place in case the business has to dissolve or the partners in the business relationship decide on a different journey in the future. Like a prenuptial agreement. Define, in writing, what constitutes an emergency, how often contributions should be made and how much they should be, percentage of ownership, etc. Keep in mind that once you do this, her creditors can access if there is ever a lawsuit and you will have to fight to get your half of the money back. Or vice versa. But really keep separate accounts. So much easier in the long run.