Put on Emergency Tax at a New Job? Here's How to Fix It Fast

Starting a new job is exciting, but there is a frustrating financial trap that trips up thousands of UK workers every year: emergency tax. If your first payslip arrives and your take-home pay is dramatically lower than you calculated, the culprit is almost certainly an emergency tax code applied by your new employer. The good news is that it is completely fixable — and you will get every penny of overpaid tax back.

Why does emergency tax happen when you start a new job?

The UK PAYE system requires your employer to know your cumulative earnings and tax paid for the current tax year before they can calculate your tax correctly. This information is contained in your P45 from your previous employer. If your new employer does not receive your P45 before their payroll cutoff, they have no choice but to assign you an emergency tax code.

Similarly, if this is your first ever job, or you have been self-employed and are switching to PAYE employment, there is no P45 to hand over — which again triggers an emergency code.

The three most common emergency codes

• 1257L W1 or 1257L M1 (Week 1 / Month 1 basis): This is the most common. The "W1" or "M1" suffix means your tax is calculated non-cumulatively — only on this pay period's earnings, ignoring the full tax year history. You will still get your monthly personal allowance, but the system won't correct for any months where you earned less or more earlier in the year.
• BR (Basic Rate): Every single pound you earn is taxed at 20% with zero personal allowance applied. This is commonly applied when HMRC suspects this is a second job.
• 0T: The most severe emergency code. No personal allowance, and the tax bands apply in full. Used when your employer has absolutely no information about your tax situation.

Step-by-step: How to fix emergency tax on a new job

1. Find your P45: Locate Parts 2 and 3 of your P45 from your previous job. Hand these to your new employer's HR or payroll department. This is the single most effective action you can take.
2. No P45? Fill in the Starter Checklist: Ask your employer for an HMRC Starter Checklist. You complete it to declare your employment situation (first job, only job, second job, self-employed before). Your employer uses this to apply the correct code without needing a P45.
3. Check your HMRC Personal Tax Account: Log into your tax account at GOV.UK. Verify your employment history is accurate and that your new employer has been added. Updating your estimated annual pay there can trigger HMRC to issue a corrected tax code to your employer within days.
4. Call HMRC: As a last resort, call 0300 200 3300 with your NI number and your new employer's PAYE reference number ready. They can update your code manually and notify your employer electronically.

How and when you get your money back

Once your tax code is corrected to a cumulative code (e.g., 1257L without W1/M1), your payroll system automatically recalculates your tax liability for the entire tax year up to that point. If you overpaid, the refund appears as a reduced tax deduction or a negative tax entry in your very next payslip. If the tax year ends before the code is fixed, HMRC will send you a P800 tax calculation and arrange a direct refund.