Managing your money

I like your ingenuity @Julianortmann !

Let me know, I am curious in how this would play out. What am I forgetting?

To read the Terms & Conditions of both the cashback & the card machine?

I think one or other card company would become suspicious long before it became a viable business & I'm pretty sure they would see it as fraud.

It might be a nice side-hustle for someone who already has a shop/business with a significant trade through a card machine but if your card is spending only at one location / card machine is taking only from one card it won't go unnoticed.

Besides that, there is usually a significant time-lag between the transaction & the payout - do you have sufficient capital to fund the first month, say?

What's the credit limit on the card?

Given that you're talking about £800 'profit' for £100,000 of turnover you would have to pay off a £5,000 limit almost daily to get a 'wage' from it.

VAT would be interesting - you could argue (from a VAT point-of-view) that it's simply moving money from one account to the other & outside the scope.  However, I think that argument might have been played out by carousel fraudsters too.

If set up as two companies, depending on how you classified the transactions (financial transactions) might not be VATable but that doesn't mean you wouldn't have to register.  But, you've just doubled your admin costs - LTD companies are not free to run!