Students are NOT exempt from paying income tax! Everyone resident and working in the UK is taxed, but only once earnings reach a certain level. In the tax year 2021-22, you can earn up to £12,570 without being taxed (£241.73 per week). This is called your personal allowance. The tax year starts in the first week of April each year. Student loans do not count as taxable income.
If you are employed, your employer should be responsible for taking any tax from your wages (this is called Pay As You Earn, or PAYE). If you are self-employed, or have taxable income from other sources (e.g. property, investments etc), then you may have to complete a self-assessment form for the Tax Office.
If you think you have paid too much tax, contact your Tax Office. If you have paid too much tax then the Tax Office can send you a repayment at the end of the tax year.
There is lots more information about students and tax at the Low-Incomes Tax Reform Group’s Tax Guide for Students.
If you earn more than £184 per week (tax year 2021-22) you will have to pay National Insurance contributions. These will be deducted from your pay and should be shown on your payslip.
If you don’t know your national insurance number you could look at old payslips, your P45 or P60, or follow the steps here: https://www.gov.uk/lost-national-insurance-number
If you need to apply for a National Insurance Number in order to work in the UK, phone the application line on 0800 141 2075.