I have a current and deposit account at HSBC. A few years ago my relationship manager there set up an arrangement whereby I maintain a set balance (say £1,000) in my current account. This coupled with a daytime facility to go overdrawn upto a set limit means I am able to push all payments through my current account without ever worrying about going overdrawn. It clears before midnight every day by transferring money from (or occasionally to e.g. just after I am paid) my deposit account.
Provided the deposit account is maintained with a reasonable buffer the system works perfectly. Come to think of it, given the negligible interest rate I get on my deposit account, the system could work just as well with 2 current accounts.
Well let’s see how it goes. It does not look like something Monzo will offer or is interested in offering. There may be something available in the future via it’s marketplace offering which is via 3rd party providers.
The “pots” implementation is very likely to not involve formally separate accounts. It’s more likely that all the money is technically in a single account but is more virtually split.
As such, if your main balance was to become negative, but you had a pot containing money which balanced that, you probably should not be charged for overdraft usage (perhaps dependent on how exactly the pot has been configured).
I would imagine you might have the option to either “protect” a pot, guaranteeing that it cannot be used as a source of funds in case of being overdrawn, in which case the above might not be the case.