Beverley Kay

My son is 21 for the last 4 years worked what he thought was not self employed however he has been fined and needs to do self assessment, he gets paid £250 a week but his wage slips is usually around £770 a month, is this right ? Can he claim back the CIS back ? Thinking of going to CAB as he works at least 50+ a week so on less than minimum wage but will it make a difference because he’s self employed Thanks