D0 Tax Code Explained | Why You’re Paying 40% Tax

Understanding the tax code is important in managing your earnings effectively, particularly if you have multiple income sources or jobs. The D0 tax code is one of the most frequently misunderstood codes in the UK tax system. If you have recently noticed this code on your payslip, you are not alone; it can significantly affect your take-home pay.

In this guide, you will learn about the D0 tax code, how it works, when it is used, and much more, so just dive into it.

What is the D0 Tax Code?

In the UK, for the 2026/2027 tax year, a D0 tax code means that all income from a specific job or pension is taxed at a higher rate of 40%. Moreover, this tax code provides no benefit of the tax-free Personal Allowance (£12,570). When your Personal Allowance is fully used on your main income, this tax code is often applied to a secondary job or pensions.

What Are the Common Situations Where Tax Code D0 Is Used

Here is a common situation where the D0 Tax code is applied:

• Second Jobs: When an individual has multiple employers, the main job typically uses the personal allowance (e.g., code 1257L), while the secondary job is subject to the higher tax rate.
• Company directors: To maintain tax efficiency, directors often accept lower salaries. They typically use a portion of their personal allowance or stay within the National Insurance (NI) threshold, while the remaining portion of their income is received as dividends. This income is taxed separately.
• Temporary Adjustments: To accurately reflect updated income, HMRC may update codes, resulting in temporary adjustments.
• Multiple Pensions: The D0 tax code may apply to pension income if an individual receives a private or occupational pension in addition to their primary income.

When Did You See D0 Tax Code On Your Payslip?

You might see the D0 tax code on your payslip if you:

• Have multiple jobs or receive income from pensions
• You have already used your entire Personal Allowance (£12,570) for another source of income.
• If you earn enough from your second income to qualify for the higher tax rate bands (£50,271 and £125,140 in England, Wales, and Northern Ireland).

Do You Get Taxed 40% On A Second Job?

Yes, if your primary employment has already used the main tax-free Personal Allowance, you are taxed at 40% on your second job. In most cases, your main job uses your entire Personal Allowance under a standard tax code, such as 1257L, so a portion of your income will be tax-free.

Your second job may be assigned the D0 tax code once this allowance is fully allocated. With a D0 code, income from that specific job or pension is taxed at 40% because your tax-free allowance and basic-rate band are already allocated to another source of income.

This often surprises employees with a second job or pension income; however, it does not necessarily indicate that you are overpaying tax. Instead, it indicates that your tax-free allowance has been used elsewhere in calculating your total income in accordance with the D0 tax code regulations.

Why has My Tax Code Changed To D0?

When HMRC determines that your total income qualifies for the higher-rate tax band and your Personal Allowance has already been allocated, they typically implement the D0 tax code. HMRC may apply the D0 tax code for several reasons:

• HMRC may apply D0 to your second job if you have a primary job that uses your Personal Allowance.
• Occupational or private pensions are frequently subject to taxation under D0 when combined with employment income.
• If your total income exceeds the basic rate limit, HMRC may immediately tax any additional income at a rate of 40%.
• Occasionally, the D0 tax code is applied due to incomplete or inaccurate information about your multiple sources of income.

What is The Difference Between D0 And BR?

To fully understand the D0 tax code, you need to know about the difference between the D0 and the BR tax code:

• One of the most notable differences is the applicable tax rate. A 40% tax is imposed on all income in D0, while a 20% tax is imposed in BR.
• D0 is typically applied when income exceeds the higher-rate threshold, while BR is used when total income remains within the basic-rate band.
• Both tax codes indicate that the tax-free personal allowance is not applied, typically because it is used in a primary job.

Is the D0 Tax Code Always Correct?

Many people wonder whether the D0 tax code can be wrong. It is not always correct and can frequently lead to an overpayment if your circumstances have changed. Especially when:

• All income earned from a job is taxed at a higher rate (40%), provided that the Personal Allowance and basic rate band have been fully used elsewhere.
• The D0 tax code may also be incorrect if your income does not fall into the higher-rate tax band.
• If you have only one job or have changed jobs.
• If your employment information has not been updated by HMRC.

What Should You Do If Your Tax Code Changes To D0?

The initial step should be to carefully review your total income rather than assuming an error has occurred when your tax code transitions to the D0 tax code. Compare your total earnings with the higher-rate tax threshold, including all sources of income, such as jobs, pensions, and other income.

Additionally, log in to your personal tax account with HM Revenue & Customs (HMRC) to verify your current employment details and tax information. If any information appears to be inaccurate, such as estimated income figures or employer details, it is important to contact HMRC and request a review. Although the D0 code is often accurate, there are instances when it may require correction or updating.

How Do I Change A D0 Tax Code?

To change a D0 tax code, you must update your information with HM Revenue & Customs. The most efficient way to do this is to use the “Check your Income Tax” online service by signing in to your Personal Tax Account. This service allows you to review employment details, remove outdated jobs, and update your estimated income.

If you are unable to access the online service, you may provide your National Insurance number and P45, if available, to the HMRC Income Tax helpline. In order to ensure that your personal allowance is applied correctly, it is important to confirm which job is your main employment if you have multiple jobs.

Will I Get A Tax Refund If D0 Is Incorrect?

Indeed, you are still eligible for a tax refund if your D0 tax code is incorrect. However, the refund will not be automatically applied to your pay cheque. You will likely need to reclaim it.

If the D0 code was incorrectly applied, resulting in a 40% tax on income that should have been taxed at 20% or tax-free. In this case, you have overpaid, and HMRC will refund the difference.

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The Bottom Line

D0 is not a penalty; rather, it is simply a way by which HMRC can tax secondary or additional income at the appropriate higher rate. It is important to verify your tax code regularly, especially if your income fluctuates or you hold multiple jobs.

When you are self-employed, manage multiple income streams, or operate a limited company, taxation can become increasingly complex. That is where right guidance is required, and our accountants are always there to help you.