0T Emergency Tax Code: Why you were taxed and how to claim a refund

Key Takeaways: 0T Tax Code Overpayments:

• Zero Tax-Free Allowance: The 0T code treats all of your earnings as taxable income, withholding an extra 20% to 45% on money that should have been completely tax-free.
• Typical Monthly Overpayment: For a standard worker, being on 0T means paying roughly £210 extra tax each month compared to the normal 1257L code.
• How to Fix It Fast: Sign in to your HMRC Personal Tax Account or contact HMRC to link your employment history. Once HMRC issues an updated tax code to your employer, your overpaid tax is automatically refunded in your very next payslip.

If you opened your payslip and found significantly less take-home pay than expected alongside the code 0T, you are currently being emergency taxed without any Personal Allowance.

What is a 0T tax code?

In the UK tax system, the standard tax code (1257L) gives you a tax-free Personal Allowance of £12,570 per year (for the 2025/2026 and 2026/2027 tax years).

A 0T code indicates:

• 0: You have £0.00 of tax-free allowance allocated to this job.
• T: The code includes other calculations, or HMRC needs to review your overall allowances across multiple income sources.

As a result, your employer must deduct 20% Income Tax from your first pound of earnings, moving up to 40% (Higher Rate) once earnings exceed the threshold, plus National Insurance.

Why did you get put on 0T?

HMRC or your payroll department will assign a 0T code in one of four situations:

1. New job with no P45: You started a new job and did not provide a P45 from your previous employer in time, or did not complete the HMRC starter checklist.
2. Second job or concurrent pensions: If you work two jobs at the same time, your full Personal Allowance is usually used up by your primary job, leaving the second job on 0T or BR.
3. Previous employer hasn't closed your record: Your previous employer has not yet notified HMRC that you left, making HMRC believe you still hold two active employments.
4. Income over £100,000: For high earners, the Personal Allowance is reduced by £1 for every £2 of adjusted net income above £100,000, reaching zero at £125,140.

How to fix a 0T tax code and get your refund

Step 1: Check your HMRC Personal Tax Account

Log in to your Government Gateway / HMRC Personal Tax Account (or the HMRC App). Under the "Pay As You Earn (PAYE)" section, check your list of current employments. If an old employer is still listed as active, mark your employment end date.

Step 2: Ensure your employer has your starter details

Ask your HR or payroll team if they received your P45 or need you to fill out the official Starter Checklist (formerly P46).

Step 3: HMRC sends an updated Coding Notice (P2)

Once HMRC corrects your record, they electronically send a revised tax code (such as 1257L) to your employer's payroll software.

Step 4: Automatic refund via your next payslip

You do not need to wait for a cheque. Under UK PAYE cumulative rules, as soon as your employer processes payroll with your corrected tax code, the payroll system automatically calculates all previous overpaid tax and adds it back as extra pay in your next wages.

What if the tax year has already ended?

If you were on a 0T code during a past tax year (ending 5 April):

• HMRC will automatically reconcile your account between June and October and send a P800 Tax Calculation letter.
• You can claim the refund directly through your HMRC online account via BACS within 3–5 working days.
• If you file Self Assessment, declare your actual P60 pay and tax deducted on your return to claim the credit.

What to gather before contacting an adviser

1. Your most recent payslip showing the 0T code and year-to-date tax paid.
2. Your P45 from your previous job (if you changed jobs recently).
3. National Insurance number and employer PAYE reference number.