How to Read Your Payslip and Spot Errors (UK)

Your payslip is the most important financial document you receive — and the least read. Most Britons glance at the bottom-line number and file it away, which is how wrong tax codes, missing pension contributions and phantom deductions go unnoticed for months. Payroll errors are startlingly common: HMRC’s own data shows millions of people sit on the wrong tax code at any given time.

This guide teaches you to read your UK payslip line by line: what every section means, the errors to hunt for, and what to do when the numbers don’t add up.

The anatomy of a UK payslip

By law, payslips must show gross pay, deductions and net pay, but most include much more. Top section — you and the period: your name, employee/payroll number, pay date and tax period (month 1–12 of the tax year, starting 6 April). Check the period first — errors often come from being paid in the wrong period. Payments: basic salary/wages, overtime, bonuses, commission, statutory payments (sick pay, maternity pay), and taxable benefits processed through payroll. Deductions: income tax (PAYE), National Insurance, pension contributions, student loan repayments, and any others (cycle-to-work, season ticket loans, union dues, attachment orders).

Year-to-date figures: cumulative gross pay and tax — your reality check against expectations. If you’ve had multiple jobs or a mid-year pay rise, these reveal whether the totals make sense. Keep every payslip (digital is fine) for at least 3–4 years — they’re evidence for tax queries, mortgage applications, benefit claims and employment disputes. And understand what your employer must provide: gov.uk’s guide to understanding your pay sets out your statutory rights.

Tax code: the number that controls everything

Your tax code tells your employer how much tax-free pay to give you before deducting tax. The standard code (1257L for recent years — 12,570 personal allowance) suits most people, but millions aren’t on it. Common variants: BR (basic rate on everything — often wrongly applied to second jobs or after employer changes), D0/D1 (higher/additional rate on everything — same issue), K codes (deductions exceed allowances — usually benefits or underpaid tax being collected), NT (no tax — rare, specific cases), and 0T (no allowances — the emergency code that over-taxes).

The emergency tax trap: start a new job without a P45 and you may be put on 0T or BR, overpaying significantly until HMRC corrects it — which can take months. Always give new employers your P45 promptly, and check your code on your first payslip, not your fifth. Verify your code anytime via your Personal Tax Account on gov.uk — if it’s wrong, you can often get it fixed online in days. Wrong codes are the single most common payslip error, and the fix is free money: overpaid tax gets refunded, but only if you notice.

National Insurance, pensions and student loans

National Insurance: employees pay 8% on earnings between the primary threshold (£12,570/year) and the upper earnings limit (£50,270), then 2% above — verify the current rates, as they change. Check you’re not paying when you shouldn’t (e.g., below the threshold across combined jobs is fine, but each job applies thresholds separately — which can mean overpayment across multiple employments). State pension entitlement accrues from NI contributions, so gaps matter long-term.

Pensions: check the deduction matches your agreed contribution rate and that employer contributions appear (they’re often shown separately or in a benefits section — their absence is a red flag). Auto-enrolment minimums are 5% employee/3% employer on qualifying earnings; salary-sacrifice arrangements show differently (lower gross pay, no separate deduction). Student loans: Plan 1, 2, 4 or Postgraduate — each has different thresholds (£24k–£27k+ depending on plan) and 9% (6% postgraduate) rates above threshold. Wrong plan = wrong deductions; graduates with multiple plan types are frequently miscoded. If any of these look off, how tax works for the self-employed is the parallel guide for when you leave PAYE behind.

Spotting errors: the monthly 5-minute audit

Run this check every payday — it takes five minutes. 1. Gross pay: matches your expected salary/overtime/bonus? 2. Tax code: still correct? (Codes change without fanfare.) 3. Tax deducted: roughly right for the period? (Cumulative figures make this easy to sense-check.) 4. NI: correct band? 5. Pension: your contribution deducted, employer’s shown? 6. Student loan: right plan, and stopped when the loan is repaid? (Overpayments after full repayment are common and reclaimable.) 7. Other deductions: every line item recognised — mystery deductions are never “just admin”.

Common finds: overtime paid at the wrong rate, bonuses taxed as if regular salary (pushing you into emergency-code territory for a month), benefits-in-kind double-counted, holiday pay miscalculated for part-timers, and the classic — being taxed on a full month after starting mid-month. Trust the maths over the assumption that “payroll must be right”. Payroll is humans with software, and both err.

What to do when something’s wrong

Step 1: gather evidence — the payslip, your contract, P60, and any relevant correspondence. Step 2: raise it with payroll/HR in writing (email, not corridor chat) — be specific: “My tax code shows BR but should be 1257L; my P45 was submitted on [date].” Most errors are fixed in the next pay run. Step 3: if payroll can’t or won’t fix it, escalate — tax code issues go to HMRC directly (your Personal Tax Account or helpline), pension issues to The Pensions Regulator, and persistent underpayment to ACAS or an employment solicitor. If disputes turn serious, understanding how to write a fair, legal redundancy letter helps you know where the lines are.

Know the timelines: tax overpayments can be reclaimed going back up to 4 years — so historical errors are worth auditing too, especially after job changes. Keep a simple log: date noticed, who you contacted, what was promised. And if an error favours you (under-deducted tax), report it — HMRC will find it eventually, and voluntary disclosure is always cheaper than discovery. The same discipline applies in reverse: an unexpected windfall on your payslip is a debt, not a bonus, until confirmed otherwise.

Conclusion

Reading your payslip is a five-minute monthly habit that protects thousands of pounds: verify gross pay, interrogate the tax code, check NI/pension/student-loan lines, and challenge anything unfamiliar in writing. Payroll errors are common, corrections are your right, and overpaid tax is an interest-free loan to HMRC you never agreed to. Start this payday — pull up the slip, run the audit, and know exactly where your money went.

Frequently Asked Questions

What does tax code 1257L mean?

It’s the standard code: £12,570 tax-free personal allowance. If you’re on anything else, check why — BR, D0 and 0T codes often indicate errors, especially after job changes.

Why am I on emergency tax?

Usually because you started a job without a P45, so payroll had no tax history. Give them the P45 promptly and check your Personal Tax Account — corrections can take weeks otherwise.

How do I check my tax code is right?

Log into your Personal Tax Account on gov.uk — it shows your current code and why. You can often correct errors online within days.

Can I reclaim overpaid tax from past years?

Yes — up to 4 years back. Audit old payslips and P60s, especially around job changes, when emergency-tax errors are most common.

What should I do about a mystery deduction?

Query it with payroll in writing immediately. Never assume small unexplained deductions are legitimate — challenge every line you don’t recognise.