If you already had a work permit with one employer and that employer gave permission to you to freelance. You can literally report the income as well đ I even paid vat on my income when I was in Thailand from my part time gigs. Illegal working is bad. But there are some rules like attending conferences and lectures on the side which are exempt from work permit rules. So English teaching etc falls into one of those when done in the right and immigration stops being bothered. Different if you worked in anyoneâs bar part time. You definitely will screwed . But yeah to err on the side of caution. Donât do it. Thereâs more things that can go wrong than just that.