The Gap Between Gross and Net: A New Starter's Guide to Reading That First UK Payslip

Your first payslip has a habit of arriving with a small, polite shock. You agreed a salary. You did the maths on the back of an envelope. Then the money lands, and it is... less. Not because anyone has made a mistake, necessarily, but because a payslip is a document with several layers. Read it like one and the gap between what you earned and what you got starts to make sense.

Gross pay and net pay: find these two numbers first

The biggest number on the page is usually gross pay: your earnings before anything is taken off. The number that actually reaches your bank account is net pay, sometimes called take-home pay. Everything between those two figures is a deduction, and each one should have a reason.

A useful habit is to ignore the emotional question — why is it smaller? — for a moment and ask a more practical one: what has been subtracted, and does each line belong to me? That turns the payslip from a disappointment into a checklist.

Tax code: the line that decides how much tax you lose

Your tax code tells payroll how much tax-free allowance to apply. The common code for many employees is 1257L, which reflects the standard personal allowance. The numbers and letters can look cryptic, but they are not random: they are HMRC's instruction to your employer about how to tax you.

Emergency tax codes are the ones that catch people out. They often end in M1, W1 or X — sometimes written after the main code, like 1257L M1. In simple terms, an emergency code means tax is being worked out on this pay period alone, without your full employment history. That can leave you paying more tax than you need to.

How does it happen? Often because a new starter has not yet handed over a P45 from their previous job, or because payroll has used a starter checklist and applied a temporary code while waiting for HMRC to update the record. It is common, fixable and worth sorting early.

Give payroll your P45 if you have one. If this is your first job, make sure your starter checklist was completed accurately. If the code still looks wrong after a couple of paydays, contact HMRC — they can issue a revised code to your employer. Do not wait until your P60 arrives at the end of the tax year. Small tax errors are easier to untangle in month one than in month ten.

National Insurance: not a savings pot

National Insurance contributions are deducted from earnings above a threshold. They are not a personal savings account, and you cannot withdraw them, but they do count towards entitlements such as the State Pension and some benefits. The letter next to your NI category — often A for standard employees — tells payroll which rules apply. Most people will not need to think about it, but it is worth knowing that it is a contribution, not a mysterious fee.

Student loan repayments: the line you might have missed

If you ticked the student loan box on your starter checklist, repayments can begin once your income crosses the threshold for your repayment plan. The money is taken by payroll alongside tax, which is why some people notice an extra deduction they were not expecting.

Plans differ, and thresholds change, so check the current figure on gov.uk if you are close to the line. A bonus, overtime or a month with extra shifts can push you over the threshold temporarily. That is normal, and the repayment is based on your income in that period. If you think the wrong plan has been applied, tell payroll sooner rather than later — a wrong plan can mean the wrong amount coming out.

Pension and the other small lines

Automatic enrolment means most eligible employees are opted into a workplace pension. You contribute, your employer contributes, and tax relief is added. Opting out can increase your short-term net pay, but you also lose the employer contribution — so it is worth understanding what you are giving up before you do it.

Other deductions might include union subscriptions, a cycle-to-work scheme, childcare vouchers, a charitable donation or a staff benefit. None of these are inherently suspicious, but they should be yours. If a line does not match something you signed up for, ask.

The month-one check

Before you file the payslip away, run a quick audit:

• Check your name, National Insurance number and job title.
• Confirm the pay period and your start date, especially if your first pay is pro-rata.
• Look at the tax code and ask whether it looks temporary.
• Compare gross pay with your contract or offer letter.
• Check each deduction line and make sure you recognise it.
• Confirm your pension and student loan position if either applies.
• Save a copy somewhere you can find it again.

That last point matters. If something goes wrong later, having a record of month one makes the conversation much easier.

When something looks off

Talk to payroll first. Be specific rather than vague: say what looks wrong, what you expected, and what date you started. If payroll cannot fix it, contact HMRC. Keep a note of who you spoke to and when. Most issues are routine corrections, not dramas.

A payslip is not a disappointment. It is a receipt with a story — gross pay, tax, NI, pension, student loan, net pay. Once you know where to look, you can spot the odd line before it becomes a year-long headache.