Second Job Tax UK: How Does It Work?

Are you considering getting a second job to earn an additional income? Well, it is a great idea. And many UK employees often think about it. But before you start, it is important to understand how Income Tax and National Insurance apply to earnings from multiple employments.

Second job tax is not a separate tax. It refers to the Income Tax and National Insurance contributions (NICs) that may apply to earnings from an additional job. Normally, you receive one Personal Allowance, which is usually allocated to your main job. This means your second job may be taxed from the first pound you earn, using a BR tax code, even if what you receive from that job is relatively small.

This article explains the tax on a second job, how it works, and how your income is treated across multiple employments. It also outlines how National Insurance is calculated and what to do if you think you have overpaid tax.

What Is The Second Job Tax?

Second Job Tax refers to the Income Tax applied to earnings from your additional employment. Your Personal Allowance is usually allocated to your main job. Depending on your circumstances, HMRC may tax all earnings from your second job under a tax code such as BR.

After the tax year ends, HMRC checks whether you have paid the correct amount of tax and may ask you to pay any tax owed or issue a refund.

The Income Tax rates applicable to your second job depend on your overall taxable income, not simply the amount you earn from that employment. HMRC considers your combined income from both jobs when determining your final Income Tax liability. While the income tax rates remain the same, your total annual income may mean you pay more tax, depending on how your pay is structured across two jobs.

How is a Second Job Taxed in the UK?

Here are the three rules that can help you explain how tax on a second job works:

1. You get one Personal Allowance, not one on every job. For 2026/27, the standard allowance is £12,570. This Personal Allowance is allocated to your main job, depending on your tax code.
2. Your tax rate depends on your combined taxable income. This means earnings from both jobs are considered together, so you could enter a higher tax band even if neither job pays enough to reach it individually.
3. Each employer calculates Pay As You Earn (PAYE) separately. Employers use your tax code to deduct Income Tax from their own payroll. HMRC receives payroll reports and may adjust your tax codes to help ensure you pay the correct amount.

What are the Income Tax Rates for 2026/27?

To understand how second job tax works, you need to know the current income tax rates in the UK. The table below shows the income tax rates:

 

Band	Income tax	Rate
Personal Allowance	Up to £12,570	0%
Basic rate	£12,571 to £50,270	20%
Higher rate	£50,271 to £125,140	40%
Additional rate	over £125,140	45%

Disclaimer: These are the income tax rates for 2026/27 for England, Wales and Northern Ireland. Scotland has different rates.

Your Personal Allowance reduces by £1 for every £2 of adjusted net income above £100,000. It is completely withdrawn when your adjusted net income reaches £125,140. The Personal Allowance and Income Tax thresholds remain frozen under the current policy until April 2031.

How Is Tax Calculated in the UK When You Have Two Jobs?

Now that you know the current income tax rates and personal allowances, let’s understand how second job tax is calculated. For 2026/27, the standard Personal Allowance is £12,570. This allowance is generally allocated through your main employment’s tax code. Your final Income Tax liability is calculated using your combined taxable income from both jobs and any other taxable sources.

In England, Wales and Northern Ireland, taxable income above £37,700 is generally subject to the 40% higher rate, after taking account of your Personal Allowance.

Each employer deducts tax through PAYE using your tax code. HMRC may adjust your tax code or reconcile any overpayment or underpayment after the tax year ends.

Second Job Tax Example

Suppose you earn £28,000 annually from your main job and £6,000 from a second job, giving you a combined employment income of £34,000. Assuming you are entitled to the full £12,570 Personal Allowance and have no other taxable income or adjustments, your taxable income is £21,430.

If your main job uses the 1257L tax code, £12,570 of your main employment income is covered by your Personal Allowance. The remaining £15,430 is taxed at 20%.

If your second job uses a BR tax code, the £6,000 earned from that employment is also taxed at 20%.

Your estimated annual Income Tax is therefore:

• Main job: £15,430 × 20% = £3,086
• Second job: £6,000 × 20% = £1,200
• Total Income Tax: £4,286

What Are The Common 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 2026/27 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: D0 taxes all income from that job at the higher rate (usually 40%), while D1 taxes it at the additional rate (45%).

Do You Pay National Insurance on a Second Job?

When you understand the second job tax, you should also know whether you need to pay NI on second jobs. Unlike Income Tax, employee NI is calculated separately for each job, using the earnings from that employment.

For 2026/27, most employees pay:

• 0% up to £1,048 a month.
• 8% on earnings between £1,048 and £4,189 a month.
• 2% on earnings above £4,189 a month.

For instance, if your second job pays £1,500 a month, you would pay £36.16 in NI, assuming standard rates and a monthly pay period.

Generally, you receive a separate threshold for each employment. If you think you have overpaid NI, you can ask HMRC to check your record and whether a refund is due.

What If My Second Job Is Self-Employment?

If you have one employed job and a second source of income from self-employment, different tax rules apply. Your employment income is generally taxed through PAYE, while your taxable self-employment profits are usually reported through Self Assessment. Your Personal Allowance applies to your overall taxable income, rather than being restricted to your employment income.

If Both Jobs Are Employed

• Your single Personal Allowance of £12,570 for the 2026/27 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.
• If you start a new job without a P45, complete HMRC’s Starter Checklist and provide accurate information about your existing employment. This helps your new employer determine the appropriate starter tax code and report your employment details correctly.
• Typically, HMRC allocates your Personal Allowance through your tax code. Contact HMRC if you think it should be allocated differently between your jobs.

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

• If your gross self-employed trading income exceeds £1,000 in a tax year, check HMRC’s rules to establish whether you must register for Self Assessment.
• 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.
• Your Personal Allowance applies to your overall taxable income, including employment income and self-employed profits, rather than exclusively to your PAYE salary.
• Your self-employed earnings are added to your employed salary. This may put you into a higher tax bracket, meaning you may owe more tax.

How to Check and Fix Your Second Job Tax Code?

You can check and review the tax code applied to your second job in the following ways:

1. Check your payslip to see which tax code your employer is currently using.
2. Check your HMRC online account or app to review your tax codes. You can also find estimated income for 2026/27.
3. Complete the Starter Checklist if you start a job without a P45, providing accurate details about your other employment.
4. Update HMRC if your jobs or income change.
5. If you have overpaid, check for a refund and claim a refund. HMRC may issue a P800, and eligible claims can be made for up to four years after the end of the relevant tax year.

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 may issue a P800 tax calculation or take other steps to collect the tax owed.

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.
• Penalties and benefit consequences depend on the circumstances. Penalties may apply if income is deliberately concealed.
• If you also receive income-related benefits, such as Universal Credit, you should report changes in earnings in accordance with the relevant reporting requirements. Your employment income may affect your entitlement. Student loan repayments are also subject to separate payroll and repayment rules.

How CAIL Can Help With Your Tax Return

Managing more than one income source can make it harder to check whether you have paid the right amount of tax. If you need to complete a Self Assessment tax return or want help understanding your tax position, CAIL is here to help.

We can help with tax return preparation and bookkeeping services.

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Bottom Line

In summary, having a second job can increase your income, but understanding how 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.