How Does Tax Work If I Get a Second Job?

Have you considered getting a second job to earn additional income? Well, you are not alone! Many people in the UK are managing multiple jobs to boost their earnings or pursuing side passions. But before you do, it is important to understand how the tax system works.

In this article, we explain how the Second Job Tax works and how your income is treated across multiple employments. We also outline practical steps to ensure you are paying the correct amount of tax.

So, let’s get into it!

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What Is The Second Job Tax?

Many people take a second job and work extra hours to make some extra money. However, this income comes with tax responsibilities. Second Job Tax refers to the Income Tax applied to earnings from your additional employment. As your Personal Allowance is usually applied to your main job, your second employer typically taxes all earnings without a tax-free allowance.

Any overpayment or underpayment is usually reconciled by HMRC at the end of the tax year. Moreover, the tax rates for the second job are the same as those you pay for your primary job. Your total combined income determines whether you pay a basic, higher, or additional rate tax. While the income tax remains the same, based on your total annual income, you may need to pay more tax, depending on how your pay is structured across two jobs.

How Is Tax Calculated In The UK?

Your total income for the year, from all the jobs combined, determines your overall tax bracket. You do not get a new Personal Allowance for each job. Each employer operates PAYE and applies a tax code issued by HMRC to collect the correct amount of tax.

What Are The Common Tax Codes For Second Jobs?

When you understand the second job tax, you should also know the tax codes for second jobs. The following are the common tax codes for second jobs in the UK:

• 1257L – This is the standard tax code for 2025/26 and provides the full £12,570 Personal Allowance.
• BR – Also known as the Basic Rate. This code is most often used for a second job. It means all your earnings from that job are taxed at the basic rate of 20%, as your Personal Allowance is already being used elsewhere.
• D0 and D1 – These codes apply if your combined income places you into the higher (40%) or additional (45%) rate bands.

How Does Tax Work If I Get a Second Job?

When working in the UK, your tax-free Personal Allowance is usually applied to your main job. This means that your second job income will likely be taxed at the basic rate from the first pound you earn. Your second job tax works in both conditions if you are employed and also self-employed.

If Both Jobs Are Employed

• Your single Personal Allowance of £12,570 for the 2025/26 tax year is typically allocated against your main income.
• Your second employer most likely uses a Basic rate tax code. It means all your income from that job is taxed at 20%.
• If both employers apply the 1257L tax code, you may underpay tax and receive a bill from HMRC after the tax year ends.
• Complete a Starter Checklist when beginning a new job if you do not have a P45. This is because you do not have a P45. This form informs HMRC that you have another job.
• If your total income from both jobs is below £12,570, you can contact HMRC to request that your Personal Allowance be split between employers.

For further guidance on the second job tax, visit the official website of HMRC. Check how and when you can inform HMRC about the additional income.

If One Job Is Employed And The Second Is Self-Employed

• You must register for Self Assessment if your self-employed income exceeds the £1,000 trading allowance.
• Income Tax on your employed earnings is collected through PAYE. On the other hand, the tax on your self-employed profits is paid through your annual Self Assessment tax return.
• HMRC applies your £12,570 Personal Allowance to your PAYE income. Your self-employed profits are added to your employment income and taxed at the appropriate marginal rate.
• Your self-employed earnings are added to your employed salary. This can put you into a higher tax bracket, meaning you owe more tax.

What Happens if I Don’t Declare My Second Job to HMRC?

If you do not declare your second employment and consequently underpay the second job tax, HMRC will eventually find out, and you will be issued a bill for the tax you owe with interest.

Your employers report your payroll information directly to HMRC, making it difficult to conceal additional employment. This can include several consequences:

• HMRC may issue a P800 tax calculation if you have underpaid tax.
• You can be charged significant penalties and fines in addition to the tax and interest you owe if HMRC finds you have intentionally failed to report your income.
• Failure to declare additional income can affect your eligible state benefits, like Universal Credit, or lead to incorrect student loan repayments.

Bottom Line

In summary, having a second job can increase your income, but understanding how the Second Job Tax works is essential to managing your finances correctly.

A different tax code may apply to each of your employments, and your overall tax liability depends on your combined income. Staying on top of things is necessary; check your tax codes, keep your payslips, and update HMRC if the circumstances change.

If you need professional guidance on Second Job Tax, contact our experienced team for personalised advice. We handle your tax process, whether it’s the registration process or filing tax returns.

Reach out to one of our professionals to get to know about the Second Job Tax in the UK. Get in touch with us, and you will be provided instant professional help!