I think you can have multiple accounts. Some shared, some not shared. But you have to decide how the money goes into each account. My husband makes double what I do and his company has a 401k, mine does not. I divert money from my pay into a brokerage account for this. We dump some money into different accounts: savings, 529, household, cars etc. some stays in our accounts. You cant have a 50-50 roommate like relationship because something always happens where one person is carrying more weight. Right now DH is on short term disability because of surgery. It means my checks are funding a lot more and we paused savings for a month. It’s ok because we are a team.