P45
What it really means
The form your employer gives you when you leave a job, showing your pay and tax so far this year. You hand it to your next employer so they use the right tax code. Keep it safe — you cannot easily get a copy.
Context, tips & common mistakes
A P45 has several parts: the employer keeps one, and you receive the rest — hand the right parts to your new employer and keep Part 1A permanently, because HMRC will not issue a duplicate if you lose it. No P45 is not a crisis: the starter checklist exists precisely for people without one, so a lost form mainly costs you a spell on emergency tax rather than any lasting problem. Employers must provide a P45 when you leave; if one drags its feet, chase payroll in writing, since you may also need the figures for benefit claims, Self Assessment or a visa application.
Check the leaving date and pay-to-date figures when it arrives — errors here follow you to the next job's tax code. If you leave the UK partway through a tax year, the P45 is also the key document for claiming any tax refund on departure.