i'm currently working 30hrs per week and want to work 8hrs extra on a saturday for another company. Will i be taxed more on the second job........i'm sure i've heard that you are/can be? or is that when you go over another tax band?
You'd pay the normal tax (20%) on it but there would be no further deductions for NI, as there would be if you worked extra hours in your existing job.
You will have to remember to declare both sets of earnings to the taxman - if there is any overpayment of tax on the second job, that will then be adjusted in your tax code on your main job (possibly for next year).
Leaving aside the NI effect it can seem that you are being taxed at a higher rate on the second job, because they are taking off 20% from the full amount without any personal allowances. So as a percentage of the total wage, the tax is higher than in your main job where you are being given your personal allowance. But it is an illusion. You get one lot of personal allowance for the year, regardless of where it is allocated. Go for it, and good luck.