PAYE (Pay As You Earn)
What it really means
The system where your employer takes income tax and National Insurance out of your pay before you get it, and sends it to HMRC. Most employees are on PAYE and never file a tax return. You can see the deductions on your payslip.
Context, tips & common mistakes
For your very first UK job there is no P45 to hand over, so the employer gives you a starter checklist instead — answer it accurately, because it decides your initial tax code and whether you start on emergency tax. If you take a second job, PAYE usually taxes it all at the basic rate under a 'BR' code; that is often correct, not a mistake, since your tax-free allowance is already used by the first job.
HMRC reconciles everyone's tax after the year ends and posts a calculation letter if you over- or underpaid, with refunds paid free and directly — so ignore adverts and texts from 'refund agents' offering to claim it for a cut. The free personal tax account on GOV.UK shows your live PAYE record, employments and code, and is the quickest way to spot payroll feeding HMRC wrong details.