[cameronbrown]

Being paid cash in hand is usually how most teenagers get their first job too. If govt. clamped down on this then you'd see a lot of youngsters struggling to get onto the market, and I believe that's why they let it slide.

[SifJar]

I'm not sure I totally buy this argument - the logic being that teenagers are only employed because employers can get away with paying them less due to lack of tax. But there are already lower minimum wages for these ages, so it'd still be cheaper than hiring older employees. Plus a lot of these jobs would be part time, so could potentially result in an income lower than the personal allowance (currently £12.5k) and be tax-free anyway