I opened a self-employed business (in the UK). As a starting budget I sent £100 from my taxed salary to my business account to have something on it. Can I send it back from my business account to my personal account without having to pay any tax on it, or any explanation why I sent it?
When you give the loan, print a sheet of paper recording it: "I, Gergö Horvath, give a loan of £100 to "Gergö's Children's Entertainment Company". And keep it. And when you return the loan, you print another sheet of paper recording it: "We, Gergö's Children's Entertainment Company, repay a loan of £100 to Gergö Horvath".
That's enough explanation. Having nothing at all is not enough. No interest payment or tax on interest payment is needed, because the interest payment on a £100 loan would be minimal and not worth the effort.