Emergency Tax Code on a New Job: How to Fix It Fast

What Are Emergency Tax Codes?

Emergency tax codes are temporary codes applied when HMRC or your employer cannot determine the correct tax code for a new employment. The most common emergency codes are:

The W1/M1 suffix means Week 1 / Month 1 — your employer applies the allowance fresh each pay period without reference to your year-to-date tax position. This is different from the standard cumulative basis where unused allowance from earlier months carries forward.

---

What Triggers an Emergency Code?

Emergency codes typically arise when:

1. You start a new job without providing a P45 — the most common cause. Without a P45 from your previous employer, HMRC doesn't know how much you've already earned or paid in tax.

2. You're starting your first job — no prior employment record exists.

3. You return to employment after self-employment — you won't have a P45 from self-employment.

4. You've lost your P45 — ask your previous employer for a duplicate or contact HMRC.

5. You start a second job — second employments typically get a BR code (all income taxed at 20%, no allowance — the allowance is already applied to your main job).

---

How 0T Code Affects Your Pay

The 0T code removes your Personal Allowance entirely for that employment. For a basic rate taxpayer earning £3,000/month:

Under 0T, you would overpay approximately £317/month compared to the correct code — that's £3,800/year if the code remained uncorrected for the full tax year.

---

The Starter Checklist

If you don't have a P45, your employer will ask you to complete the Starter Checklist (previously known as the P46). You choose one of three statements:

Choosing the wrong statement can lead to a wrong code. If you're in doubt:

• Statement A is for most straightforward new starters with no other employment
• Statement B if you have multiple concurrent jobs
• Statement C if you finished another job earlier in this tax year

Your employer submits the Starter Checklist to HMRC electronically via RTI (Real Time Information) — usually alongside your first payroll submission.

---

Step-by-Step: Getting the Right Code

Step 1: Find your P45

Ask your previous employer for your P45. If you've lost it, your previous employer should provide a duplicate. The P45 shows:

• Your tax code at time of leaving
• Your pay and tax deductions in the current tax year to date
• Your National Insurance number

Step 2: Give P45 to your new employer

Provide all 3 parts of the P45 to payroll/HR on your first day or as early as possible. The employer enters these figures into their payroll system.

Step 3: Check your first payslip

When you receive your first payslip, check the tax code shown. If it shows W1/M1 suffix or 0T, the correct code hasn't arrived yet. This is normal for the first month — your employer may be awaiting HMRC's instruction.

Step 4: Contact HMRC if the code isn't updated by month 2

If your second payslip still shows an emergency code, contact HMRC:

• Online: Login to your HMRC Personal Tax Account at gov.uk
• By phone: 0300 200 3300 (Mon–Fri 8am–6pm)
• Via the HMRC app

HMRC can update your code immediately and issue a P6 instruction to your employer.

Step 5: Confirm the updated code with payroll

Once HMRC issues a new code, your employer's payroll system receives a P6 notification. The new code should apply from the next pay run. Confirm with HR/payroll that this has been received and applied.

---

Reclaiming Overpaid Tax

If you've overpaid tax due to an emergency code, there are two ways to reclaim:

Automatic PAYE correction

If your correct code is applied before the tax year ends (5 April), PAYE operates on a cumulative basis. The system automatically calculates the year-to-date correct tax position and adjusts your deductions going forward. In months after the correction, you may notice reduced tax deductions — this is PAYE refunding the overpayment in real time.

Example: 0T code for 2 months, correct 1257L applied month 3

• Months 1–2: Overpaid £634 (£317 × 2)
• Month 3 onwards: PAYE calculates cumulative correct position and deducts less for remaining 10 months
• By April 5: Net tax position is correct

End-of-year P800

If you leave the job, finish the tax year, or the correction happens late, HMRC reconciles your position via a P800. You'll receive a P800 by post or through your HMRC online account:

• If you've overpaid: refund sent automatically (bank transfer if account registered, otherwise cheque)
• If you've underpaid: collection notice issued, usually via the following year's tax code

Claiming early (R40 form)

If you've left employment mid-year and won't receive a P800 until the following tax year, you can claim a refund now using form R40 (claim for repayment of income tax). Submit this after the tax year ends (after 5 April) and HMRC processes it within 4–6 weeks.