I’m going to resurect this thread because I’ve just heard of this feature and was puzzled as well as to its use. I can see one way an automation could help people with (very simple) tax, but this isn’t it.
If you are using a business bank account and ensuring all money goes through it - income and expenses, then it’s contents will be your profits.
If you know roughly how much you want to put aside for tax, eg 25%, then the automation should happen when moving any money to your personal account.
Example. You have £10,000 in your business bank account. You’ve decided you want to keep 25% of profits aside for tax. You’ve made sure all expenses came out of that account as well as income in. So it’s your profit. Monzo does nothing as money comes in and out of that account, but if you try to transfer £500 to your personal account, it prompts you to transfer 25% to a tax pot because you’re taking £500 out of the business account early and you might want the tax for that amount kept aside.