But that is nothing more than breach of contract ummmm (if anything) and then only if the bank says "you cannot pay business funds into your personal account". I've got a business account and a personal account and I'm always swapping round between the two (largely because some people still pay into my personal account which was my sole account until I had a business account and i've never got round to telling them). If my bank told me I was committing fraud, I'd tell them to sling their hook.