A lower-than-expected payslip after starting a new job, returning to work or taking on an additional role can be unsettling. An emergency tax code is often the reason. It does not necessarily mean HMRC believes you have done anything wrong, but it can mean that your employer does not yet have enough information to calculate your Income Tax using your full position.
For employees, the priority is to provide the right details quickly and check that a revised code has been applied. For business owners and employers, the focus is on processing starters correctly, using payroll software carefully and acting promptly when HMRC issues a coding notice. Small administrative delays can affect a member of staff’s take-home pay and create avoidable questions for the business.
What is an emergency tax code?
An emergency tax code is a temporary tax calculation used where payroll records are incomplete or HMRC has not yet matched an employee to the correct tax details. It commonly appears with a suffix such as W1, M1 or X. These indicators mean tax is being worked out on a non-cumulative basis – usually by looking at that week or month in isolation rather than taking account of pay and tax across the whole tax year.
For many taxpayers, the standard code is 1257L, reflecting the usual £12,570 Personal Allowance. That code may be followed by W1, M1 or X while information is being checked. The number and letter can differ where an individual has benefits in kind, taxable income elsewhere, an adjustment for previous tax, or a different entitlement to allowances.
A non-cumulative code is not always more expensive in every pay period, but it can prevent earlier unused allowance from being considered. That is why somebody who has had a gap between jobs, or who has paid little tax earlier in the year, may initially pay more Income Tax than expected.
It is worth separating this from other codes that can also look alarming. A 0T code generally means no tax-free Personal Allowance is being given through that employment. A BR code taxes all pay from that job at the basic rate, which can be correct for a second job or pension. Neither automatically means an error, but both deserve a check if they do not reflect the employee’s circumstances.
Why an emergency tax code is used
The most common trigger is a change of employment. If a new employer does not receive a P45 in time, they will ask the employee to complete a starter checklist. This helps payroll establish whether it is the person’s first job since the start of the tax year, their only job, or an additional job alongside another source of income.
Problems can arise when the checklist is not returned, is completed incorrectly or reaches payroll after the first pay run. A P45 can also be delayed if a previous employer has not processed someone as a leaver. In other cases, HMRC may simply need time to update records following a move between jobs, a new pension, a change in benefits or an adjustment to estimated income.
An emergency basis can also be used where someone returns to the UK, begins work for the first time, or has a complicated mix of employment and self-employment income. The code is a practical holding position, not a final judgement on the tax due.
For directors and owner-managers, the situation can be less straightforward. Salary, benefits, dividends and another employment can all influence the wider tax picture. A payroll tax code only deals with Income Tax collected through PAYE. It does not settle the tax position on dividends or other income, which may still need to be dealt with through Self Assessment.
How to check an emergency tax code on a payslip
The tax code should appear on the payslip, usually close to gross pay and tax deductions. Look not just at the number and letter, but also for W1, M1 or X. Those suffixes are often the clearest sign that a week 1 or month 1 calculation is being used.
Next, compare the code with your circumstances. If you have recently changed jobs and gave your new employer a P45 or completed a starter checklist, ask payroll whether it has been received and processed. If you have more than one job, check that your Personal Allowance is allocated to the employment where it will be most useful. HMRC normally makes this decision, but incorrect or out-of-date estimates can lead to an unsuitable split.
Employees can also review their PAYE details through their HMRC Personal Tax Account. This is particularly useful where expected annual pay has changed materially. For example, a bonus, reduced hours, unpaid leave or a new role may mean HMRC’s estimate no longer reflects reality.
Do not assume every lower payslip is caused by the tax code. National Insurance, pension contributions, student loan repayments, salary sacrifice arrangements and workplace benefits can all affect net pay. Looking at the full payslip before raising a query gives payroll and HMRC a clearer starting point.
What employees should do next
The simplest route is usually to speak to the payroll contact at the new employer and provide any missing information. A P45 should be handed over as soon as it is available. If it cannot be obtained, the starter checklist needs to be completed accurately.
If the payroll team has the correct information but the code still appears unsuitable, the employee should contact HMRC or update the relevant details through their Personal Tax Account. HMRC, rather than the employer, decides the tax code. Once it issues a new coding notice, the employer should apply it in the next available payroll run.
Keep copies of payslips, the P45 and any correspondence until the position is corrected. This is especially sensible for anyone who has changed roles more than once in a tax year, receives a pension alongside employment income, or expects to file a Self Assessment tax return.
What employers need to get right
For a small business, a starter’s first payslip is an early test of how well payroll administration is working. Employers should collect starter information before the payroll cut-off wherever possible, enter it accurately into the payroll system and submit the required PAYE information to HMRC on time.
If a P45 arrives after the employee has been paid, it should still be processed in line with payroll guidance. The revised information may allow the payroll software to calculate tax cumulatively and correct an earlier overpayment through a later payslip. Employers should not manually select a more favourable tax code to help an employee receive more net pay. Only HMRC can authorise a change through an official notice.
Clear communication matters as much as the calculation. Explain that a temporary code may be corrected once HMRC’s records catch up, without promising a particular date or refund. Where an employee is worried, confirm what information has been received, whether it has been submitted, and whether any action is still needed from them.
Growing businesses should also consider the wider cost of inconsistent payroll records. Repeated starter errors create employee frustration, take management time and can make year-end reporting harder. Reliable bookkeeping and payroll processes give directors better visibility over staff costs while reducing preventable compliance issues.
When will overpaid tax be refunded?
If HMRC issues a cumulative tax code during the same tax year, payroll will often make an automatic adjustment. The refund may appear through a later payslip, although the amount and timing depend on pay to date, the new code and when it is applied.
If the position is not corrected before the tax year ends, HMRC may review the records and issue a P800 calculation where a repayment is due. People who complete a Self Assessment tax return will generally have the final position calculated through that process instead. There are situations where no refund is due – particularly where the temporary code reflected the correct tax on a second income or where tax is owed on other income.
A code that remains unchanged for several pay periods is worth chasing, particularly if the employee has supplied all the requested details. Waiting until the end of the year can leave someone short of cash unnecessarily.
Get practical support when PAYE is not straightforward
Most emergency tax code issues are resolved once accurate information reaches HMRC and payroll applies the revised notice. However, the right answer depends on the whole income picture, not solely on the code shown on one payslip. This is particularly true for directors, landlords, self-employed people moving into employment and anyone with multiple income sources.
At RK & Co, we help Greater Manchester business owners and individuals make sense of PAYE, payroll records and wider personal tax obligations in plain English. A timely review can turn a confusing payslip into a clear action plan – and help ensure tax administration supports financial confidence rather than distracting from the work ahead.