Also, I don't understand why you would think that SW would be exempt from paying taxes, or N.I for that matter? You are running a small business and it is not illegal. Frankly though, you can tell HMRC any job title you want, they don't care. They will care though if some arsehole grasses you up to them and you've been earning money every week you haven't told them about. You also may not qualify for your pension or benefits in the future if you don't pay your N.I.