Understanding Your Payslip: Tax Codes and Deductions

Payslips are designed by payroll departments for payroll departments. Most people check the amount at the bottom, confirm it looks roughly right and file it unread.

That is understandable and mostly harmless, until the month it is wrong. Errors in tax codes, student loan deductions and pension contributions are more common than people expect, and they are usually the employee who spots them.

Here is what each part means. This is general information rather than financial advice.

Gross pay is where it starts.

Gross pay is the total before any deductions. For salaried employees it is usually the annual salary divided by twelve, with overtime, bonuses and commission added separately.

Below it you should see a breakdown of each element, along with year-to-date totals showing what you have earned and paid since the start of the tax year.

The UK tax year runs from 6 April to 5 April, which is why year-to-date figures reset in April rather than January.

Your tax code drives the income tax.

The tax code tells your employer how much tax-free income you are entitled to. It usually consists of numbers followed by a letter.

The numbers represent your tax-free allowance for the year with the final digit removed, so a code of 1257L indicates a tax-free allowance of £12,570. That figure has been the standard personal allowance in recent years, but thresholds change, so check the current position rather than assuming.

The letter indicates circumstances. L is the standard code, BR means all income from that job is taxed at basic rate, which is normal for a second job, and D0 indicates higher rate throughout.

Codes ending in W1, M1 or X are emergency codes, applying tax on that period alone rather than cumulatively. They typically appear after starting a new job without a P45 and usually resolve automatically, though they can result in overpayment in the meantime.

If your code changes unexpectedly, HMRC will normally write to explain why. Common causes include company benefits, underpayments from a previous year being collected, or multiple sources of income.

National Insurance works differently from tax.

National Insurance contributions are calculated on each pay period in isolation rather than cumulatively across the year, which is why they can vary between months with irregular earnings.

Your payslip shows an NI category letter reflecting your circumstances, with the standard category applying to most employees. Different letters apply to those over state pension age, certain apprentices and some other groups.

NI contributions build entitlement to the state pension and certain other benefits, based on qualifying years rather than the amount paid.

Student loan repayments depend on the plan.

Student loan deductions only begin once income exceeds a threshold, and the threshold depends on which repayment plan applies.

Several plans exist, determined largely by where and when you studied, and postgraduate loans are collected separately and can appear as an additional deduction alongside an undergraduate one.

Deductions are taken on income above the threshold rather than on the whole salary. If you have finished repaying but deductions continue, contact your employer and the Student Loans Company, as overpayments are recoverable.

Pension contributions may be shown in different ways.

Under auto-enrolment, most employees are enrolled into a workplace pension unless they opt out, with both employee and employer contributing.

How it appears on the payslip depends on the scheme. Under net pay arrangements the contribution is taken before tax is calculated, so the tax relief is automatic. Under relief at source it is taken after tax and the provider reclaims basic rate relief.

Salary sacrifice arrangements reduce gross pay in exchange for an employer contribution, which also reduces National Insurance. If your gross pay looks lower than your stated salary, this is frequently the explanation.

Higher rate taxpayers in relief at source schemes may need to claim additional relief through a tax return, which is easily missed.

Other deductions vary by employer.

Common additions include season ticket loans, cycle to work schemes, workplace charity giving, union subscriptions, healthcare schemes and childcare arrangements.

Court-ordered deductions such as attachment of earnings orders also appear here.

Each should be clearly labelled. Anything you do not recognise is worth querying with payroll rather than ignoring.

Net pay is what actually arrives.

Net pay is gross pay minus all deductions, and it should match the amount credited to your account.

Payslips must legally be provided to employees, and since 2019 they must show hours worked where pay varies by hours.

Keeping payslips matters. They are frequently required for mortgage applications, tenancy references and benefit claims, and they are the evidence if a dispute arises.

Know your other documents.

A P60 is issued after the end of each tax year, summarising total pay and deductions for that year from that employer. Keep them.

A P45 is issued when you leave a job and passed to your next employer to ensure the correct tax code is applied. Without it, emergency tax is likely.

A P11D details taxable benefits provided by an employer, such as a company car or private medical cover.

Check your position online.

HMRC provides a personal tax account allowing you to view your tax code, check your income record, see your state pension forecast and report changes.

It is free, reasonably straightforward and the quickest way to confirm whether a tax code is correct.

If you believe you have overpaid, refunds can generally be claimed for several previous tax years, so it is worth checking even for older errors.

Share your thoughts.

Have you ever found an error on your payslip that nobody else spotted?