Lower take-home pay can come from lower earnings, higher deductions or another payroll adjustment. Start by comparing the same pay period on two original payslips. The checklist below gives possible explanations, not a diagnosis or a promise that the deduction is correct.
1. Your tax code changed
A changed code or calculation basis can affect PAYE tax. W1, M1, X or NONCUM indicates an emergency basis; 0T alone does not. A change can mean too much or too little tax, so do not assume a refund is due. Compare the full code with your HMRC notice and read our 1257L explanation.
2. National Insurance moved
Employee National Insurance depends on relevant earnings, thresholds and your category. A bonus or overtime may change the deduction. If it moves unexpectedly, ask payroll to explain the earnings used and the category applied; Income Tax and NI are not interchangeable.
3. Pension contributions changed
Joining a pension or increasing contributions can reduce cash take-home pay. Compare the scheme's pensionable earnings and contribution method, not just the headline percentage. Ask payroll or the pension provider about anything you do not recognise.
4. Hours, overtime or pay rate differences
Compare basic pay, hours and overtime before deductions. Different cut-off dates, unpaid time or the end of temporary extra hours may explain a change. Net pay does not necessarily move by the same amount as gross pay.
5. A bonus or commission month
Check whether the comparison month included a bonus or commission that you did not receive this time. A larger payment can change PAYE deductions; the outcome depends on your code and year-to-date figures. Do not assume all additional tax will be refunded.
6. Salary sacrifice changes
Salary sacrifice exchanges cash salary for a benefit. The tax and NI treatment depends on the benefit and arrangement: not every scheme reduces both. Ask payroll for the agreed change and how it appears on your payslip.
7. Student loan deductions
Repayments depend on the loan plan and earnings in the pay period. A bonus can trigger a deduction even if your annual earnings later fall below the yearly threshold. Confirm the plan with payroll or the Student Loans Company; the payslip may not name it.
8. Arrears from an earlier period
A correction or recovery of an earlier overpayment can affect this payment. Ask payroll what period it relates to, how the amount was calculated and why the deduction is permitted. Do not assume an unexplained deduction is simply tax arrears.
9. Other payroll adjustments
Court-ordered deductions or agreed subscriptions may affect net pay. Benefits such as a company car may instead affect taxable pay or your tax code. Request an explanation of the presentation and the reason for the change.
How to investigate in five minutes
- Compare this payslip with the previous one, line by line
- Identify which lines changed and by how much
- Check the tax code and NI table letter against your records
- Ask payroll in writing about any unexplained figure, naming the line and pay period
- If the issue is your tax-code information, check it with HMRC rather than asking payroll to choose another code
Frequently asked questions
Will emergency tax correct itself?
It may be temporary, but the outcome depends on HMRC receiving the right details and your circumstances. Check your record and follow HMRC's guidance if the code still looks wrong. Do not rely on a fixed number of paydays or assume a refund will be automatic.
My gross pay is the same — why did net pay drop?
Look for changed deductions, taxable benefits or non-wage adjustments. Compare the whole payslip and the payment received, not just the basic salary line.
A simple comparison example
Fictional example, not a tax calculation: last month gross pay was £2,800 and total deductions were £600, leaving £2,200. This month gross pay is £2,700 and deductions are £575, leaving £2,125. Take-home pay is £75 lower: £100 less gross pay, partly offset by £25 less deductions. The subtraction explains the difference, not whether the deductions are correct.
Read the payslip walkthrough or explore MyPay to organise and compare your confirmed pay records. MyPay is not a payroll audit or a substitute for HMRC or professional advice.
Editorial check: 22 October 2026. Tax context: 2026/27 UK tax year; actual deductions depend on personal circumstances and jurisdiction. General education, not personalised tax or financial advice.