Emergency Tax Codes: Why You Were Put on W1/M1 and How to Fix It

Starting a new job should be a positive milestone, but it can be frustrating if you receive your first payslip and find your income heavily reduced by an emergency tax code. HMRC uses emergency tax codes temporarily when they do not have enough information about your taxable income or previous employments. This guide explain how emergency tax codes function, how to recognize them on your payslip, and how to get them corrected quickly.

How to Spot an Emergency Tax Code on Your Payslip

HMRC has three standard emergency tax codes for the current tax year. If you see any of the following codes printed on your payslip, you are currently being taxed on an emergency basis:

• 1257L W1 (Weekly basis)
• 1257L M1 (Monthly basis)
• 1257L X (Non-cumulative basis)

These codes mean that your tax-free allowance is calculated in isolation for that specific pay period. Your employer will calculate your tax based only on what you earn in that week or month, completely ignoring any previous tax you paid or allowances you used earlier in the tax year.

Why Was I Put on an Emergency Tax Code?

HMRC will instruct your employer to use an emergency code if:

• You started a new job and your previous employer has not yet issued a P45 form to your new employer.
• You started your first job, or you are working after a period of self-employment, and did not complete the New Starter Checklist.
• You have multiple sources of income or started receiving a state or private pension mid-year.

How to Correct Your Code and Claim Back Excess Tax

To fix an emergency tax code, your new employer must receive your P45 from your previous job. If a P45 is unavailable, request a **New Starter Checklist** from your payroll department, fill it out accurately, and return it. Your employer will submit these details to HMRC. If the emergency code persists, you can contact HMRC directly via phone or update your employment details inside your HMRC Personal Tax Account. Once your tax code is updated, your employer will automatically refund any excess tax you paid in your next payroll cycle.