Please help, I haven’t a clue! Tax query

So, I am currently employed 22.5 hours a week but I am going to do some work where someone will pay me to do some extra work. I don’t know where to start in regards to paying tax. Will I pay more tax as I will have 2 jobs? Do I just pay tax at the end of the financial year? I have no idea what I am doing so any advice would be appreciated. Thank you

Hi Gemma,
The tax free allowance for 2024/25 is £12,570. So this is then given over the course of the tax year Apr 24 - March 25, so this allows you to earn 1047.50 every month before tax is deducted. after you would be taxed at basic rate (20%).
If you have just 1 employer this allowance is set against that source, if you have 2 part time employments you can contact HMRC to request your allowance be split between the 2 sources of income: ie £600 tax free per month at one source and £447 tax free at the other source. Anything that goes over the tax free amounts split would then be taxed accordingly.
Pleae contact HMRC when both sources of income have started and we can see if this is possible - Income Tax: general enquiries.
Thank you.