Postby MGMidget » Mon Aug 19, 2013 1:28 pm
I would guess that her previous employers have paid cash for extra work not in her contracted hours and nanny has gone along with this taking cash. If she's declared on a tax return it its possible a retrospective tax charge might apply if her employers didn't declare it and pay tax at the time and if she didn't list it as 'self employed' income (and of course, have already registered a self employed business with HMRC). If you have agreed a 'net' payment contract with your nanny you might get clobbered with the extra tax bill as her tax code will change. Hopefully you've agreed a gross pay figure! More likely, however, the cash amounts weren't declared by either party.
To answer your question, no, if you are planning to pay cash with the idea that the nanny sorts out her own tax on this part by registering as self employed for babysitting, I don't think it would work. I'm sure the nanny's extra hours would be regarded as 'overtime' by HMRC and hence subject to employment tax like the rest of her job. You've already put one night's babysitting in her contract so that suggests that babysitting is part of her job anyway. I'm not a lawyer though, that's just my opinion!
I think you are compromising yourself if you go along with the nanny's suggestion.