This is going to be an interesting one! I think the requirements will vary a lot more from business to business than they do from person to person.
Let’s use my business as an example: we’re a small pub company. The turnover reported in our accounts is about £1.7 million per year. That’s excluding VAT, though, so the actual cash that comes in is £2 million.
Our current account doesn’t accumulate money over time, so whatever comes in must go out again. That’s about £5.5k per day (or £7.7k per day if you only include weekdays) — so, well within Monzo’s existing limit of £10k per day on the personal accounts.
However, we don’t pay out at a constant rate. Some days we don’t pay anyone anything at all! Once a month we pay all our staff, once a quarter we pay our VAT, and once a year we pay corporation tax and dividends. Very occasionally we make even larger payments, for example when we buy a new pub.
To deal with these payments, we have a limit of £100k outgoing per day on our current current account.
We find it adequate: usually we’re nowhere near that, but once or twice per year we get close to it. (When we know there’s a very large payment coming up we can plan to make it over more than one day.) I wonder whether this limit (5% of annual receipts) would be appropriate to most businesses, or whether there’s a lot of variation per industry?