So I want to follow on from the above and list out a possible quick win idea.
Recently the concept of Coin Jar was created to try out rules/automation. What I would like to suggest is another concept for DD Jar.
So Direct Debits leave the account at say 02:00-04:00 on the due date. So a transfer into the main account from a pot ideally needs to be 00:01-01:30 to ensure it is in place for the debit to leave.
So I think the fantastic devs at Monzo could create the following.
User sets up pot with the name Direct Debits
User puts enough money in pot to cover all direct debits.
Monzo receive notification of Direct Debit amount and due date.
Monzo schedule a transfer from Direct Debits pot for the same amount(s) into main account at 01:00
Direct Debit is paid 02:00 as the funds are now in the right place.
Perfect we now have a way to manage Direct Debut payments while separating the funds from the main account.
Some time later you could then customise the messages to advise there are not enough funds in the DD pot/main account etc. So users are notified if a direct debit is likely to be rejected.
Any Monzo dev want to take this up as a challenge @simon