Most people check one number on their payslip: the money in. But payroll errors are surprisingly common — wrong tax codes alone cost workers hundreds of pounds a year — and every error is visible if you know where to look.
The Tax Code — Check This First
1257L is standard: £12,570 of allowance, spread across the year. Red flags: BR (all income taxed at 20% — commonly left over wrongly from second jobs), 0T (no allowance at all), W1/M1 (emergency non-cumulative basis, normal after a job change but should not persist past a couple of months), and K codes (negative allowance — check you understand why).
The NI Letter
Category A is standard. C means over state pension age (no employee NI). If you are on A but past pension age, you are overpaying every month.
Year-to-Date Columns
The YTD figures let you verify the whole year at a glance: annualise your YTD gross, run it through an income tax calculator, and compare with YTD tax paid. A mismatch of more than a few pounds means a conversation with payroll.
If Something Is Wrong
Tax code errors: contact HMRC (not your employer — they just apply the code) via the Personal Tax Account. Refunds for the current year arrive through your next payslip automatically once the code corrects.