Why Your Tax Code Changed to BR or 0T
Your tax code will change to BR or 0T if HMRC lack payroll details, you start a second job, or taxable benefits absorb your dynamic personal allowance. Here is how to fix it.
Your tax code changes to BR or 0T when HM Revenue and Customs (HMRC) removes your standard tax-free Personal Allowance. This typically happens when you start a new job without providing sufficient payroll history, take on a second job, or earn over a certain limit. Under both codes, you are taxed on every pound of your earnings, though they apply different tax bracket mechanics depending on your income level.
Key takeaways
- The BR code applies a flat 20% basic tax rate to your entire income from that specific source, with no Personal Allowance available.
- The 0T code also removes your Personal Allowance but applies progressive tax brackets, meaning your income can be taxed at 40% or 45% if you earn more.
- These codes are often triggered by a missing P45, starting a second job, or having employer-provided taxable benefits.
- You can resolve an incorrect code by submitting a Starter Checklist to your employer, updating your details on your HMRC online account, or calling HMRC directly.
Why is my tax code suddenly BR or 0T?
Your tax code has changed because HMRC does not have the necessary payroll information to grant you a tax-free Personal Allowance on this source of income.
When you have the standard tax code, the first portion of your earnings is tax-free. Under both the BR and 0T codes, your Personal Allowance is completely stripped away. This represents a significant change to how your net salary is calculated each month.
The major mechanical difference lies in the tax rates applied. The BR code treats all earnings as basic-rate income, while the 0T code evaluates your overall earnings progressively. If you are on a 0T code, high earnings will quickly push you into the higher or additional-rate brackets, resulting in substantially larger tax deductions on your pay slip.
What is the difference between tax code BR and 0T?
The primary difference is that the BR code taxes all income at a flat 20% rate, whereas the 0T code subjects higher levels of income to the progressive 40% and 45% tax bands.
If you hold a BR code, your payroll provider applies a flat basic rate of 20% across all taxable earnings, regardless of how much you earn from that job. If you hold a 0T code, your employer applies no Personal Allowance but must still respect the progressive UK tax bands. This means that once your cumulative pay crosses the basic-rate threshold, your employer must deduct 40% tax, and eventually 45% tax if your earnings are high enough.
| Tax Code | Income up to £50,270 | Income from £50,271 to £125,140 | Income over £125,140 |
|---|---|---|---|
| BR (Basic Rate) | Flat 20% tax | Flat 20% tax | Flat 20% tax |
| 0T (Zero T) | 20% tax | 40% tax | 45% tax |
Is BR or 0T an emergency tax code?
No, standard emergency tax codes are calculated differently because they still offer you a portion of the tax-free Personal Allowance throughout the year.
True emergency tax codes are typically identifiable by the suffixes W1, M1, or X. According to official HMRC operational guidance, these suffix codes are non-cumulative, meaning your tax is calculated solely on your earnings in that specific week or month. However, unlike BR and 0T, emergency codes still allocate a portion of the £12,570 Personal Allowance to each pay period so you do not pay tax on your entire salary.
6 common reasons why your code has changed
Your tax code changes to BR or 0T due to administrative gaps, holding multiple sources of income, or reaching specific statutory earn thresholds.
- Missing P45 or Starter Checklist: If you start a new job and do not provide a P45 from your old employer or complete a Starter Checklist, your new employer must apply a 0T code on a non-cumulative basis.
- Second jobs and dual employments: Under the UK PAYE framework, your £12,570 Personal Allowance is allocated to your main job. HMRC will automatically apply a BR code to any second job or secondary pension.
- Taxable benefits reducing allowance to zero: Benefits in kind, such as a company car or health insurance, are offset against your tax-free allowance. If the value of these benefits exceeds £12,570, your allowance becomes nil, and HMRC will issue a 0T code.
- Collecting prior-year underpaid tax: If you owe Income Tax from a previous tax year, HMRC can adjust your current PAYE code. If the underpayment is substantial, HMRC may reduce your current allowance to zero to recover the debt.
- The £100,000 Personal Allowance taper: Your Personal Allowance is reduced by £1 for every £2 of adjusted net income earned over £100,000. It is completely withdrawn at £125,140, meaning HMRC will issue a 0T code for incomes above this point.
- New tax year rollover issues: When transitioning to the 2026/27 tax year starting 6 April 2026, employers must update tax codes in line with the official HMRC P9X guidance. If HMRC has not sent updated instructions and the employer has insufficient historical pay data, the system will apply a 0T code.
UK tax rates and thresholds for 2026/27
Understanding how the BR and 0T codes deduct tax from your earnings requires familiarity with the standard allowances and tax thresholds in place for the current tax year.
| Tax Parameter | Statutory Value (2026/27) |
|---|---|
| Standard Personal Allowance | £12,570 |
| Basic Rate (20%) Threshold | Income up to £50,270 |
| Higher Rate (40%) Threshold | Income from £50,271 to £125,140 |
| Additional Rate (45%) Threshold | Income over £125,140 |
| Personal Allowance Taper Start | Income over £100,000 |
How do I fix my tax code and get my money back?
You can resolve an incorrect tax code and claim a refund by updating your employment details directly with HMRC or submitting missing paperwork through your employer.
- Check your PAYE Coding Notice: Review the P2 Coding Notice sent by HMRC to find the specific rationale they used for altering your tax code.
- Complete your Starter Checklist: If you recently started a new job, ask your employer's payroll team for a Starter Checklist, complete it, and return it to them immediately.
- Update your details via your Personal Tax Account: Log into the official government portal and use the 'Check your Income Tax' service to update your estimated income and benefit details.
- Contact HMRC directly by phone or chat: If your online portal does not resolve the issue, call HMRC on 0300 200 3300 to request manual verification of your employment status.
- Await your payroll adjustment and tax refund: Once HMRC updates your code, they will notify your employer. Any overpaid Income Tax from the current tax year will be adjusted and refunded automatically in your next paycheck.
What should I do if my employer has put me on a BR tax code?
You should check if you have completed a Starter Checklist for your employer. If you have not done so, submit this form immediately so your payroll department can forward your details to HMRC and secure your correct tax code.
Will I get a refund if I overpaid tax on a 0T code?
Yes. Once HMRC issues your correct tax code and notifies your employer, any overpaid tax from the current tax year is normally calculated by your employer's payroll software and refunded to you in your next pay packet.
How long does it take HMRC to change my tax code back to normal?
It generally takes HMRC between one and two weeks to process your updated information and issue a new tax code notice. Once your employer receives the electronic notice from HMRC, they will apply the correct code in the next available payroll run.
Why is my second job taxed at the basic rate on a BR code?
Your secondary job is taxed at the flat basic rate of 20% through a BR code because your standard £12,570 Personal Allowance can only be applied to one job. This prevents you from receiving a double tax-free allowance across multiple employments.