'We created a spreadsheet': how couples manage their cash
You don’t need to be married to have a joint account, own a property together or find that your partner’s finances affect you – for example, if you live with them and either of you tries to claim universal credit, all of your savings will be taken into account. For other things, the link is not made automatically and you will need to do some paperwork. If, for example, your company offers a death-in-service benefit, you should tell it who you want the money to go to should you die. The same is true of your pension and any life insurance.
Source: theguardian.com