Pepa

Hello and thank you for this forum, it's very useful. I have a full-time job where I earn about £32000 a year. I'd like to do some language teaching, a couple of evenings a week, without reducing the hours of my full-time job. Tax for my current job is paid by the company (deducted from the money I take home every month), but how would I pay tax for the second job if I'm a private tutor (not working for a company)? And what percentage? Thank you.