UK tax system: tax brackets, PAYE & 60% tax trap

If you are a full-time employee in the UK, your employer most likely pays your taxes through PAYE (Pay As You Earn). In simple terms, it is a system employers use to deduct income tax and National Insurance (NI) directly from your wages before you even see them. While this makes life easier for most, understanding the underlying concepts is essential for managing your finances effectively as an expat.

In this guide, we will cover the most common concepts that often overlap:

• Tax brackets (the "buckets")
• Tax codes (your "permission" to earn tax-free)
• Personal Allowance (how much you keep 100%)
• The 60% "Tax Trap" (the £100k hurdle)
• Hidden taxes like Student Loans and Child Benefit charges

Understanding these is crucial for anyone trying to navigate the cost of living in London or planning for long-term investments.

UK Income Tax Brackets Explained (2025/26 Rates)

Consider tax brackets as buckets of money you have to pay tax on. These brackets and the Personal Allowance are set by the Chancellor of the Exchequer. For the current 2024/25 and upcoming 2025/26 tax years, most thresholds remain frozen, a phenomenon often called "fiscal drag."

Income tax is charged at three main progressive rates according to the official GOV.UK guidelines:

| Band | Taxable 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% |

UK Income Tax Brackets - Visual representation of tax rates on different income levels

The 60% Tax Trap: What Happens When You Earn Over £100,000

There’s a catch known as the "60% tax trap". When your income exceeds £100,000, your Personal Allowance (£12,570) begins to taper off. For every £2 you earn above £100,000, you lose £1 of your tax-free allowance.

This creates a very high effective tax rate. Let’s look at an example. Anna is a Senior Software Engineer earning £100,000. Her company offers £250 for a weekend on-call shift.

• Income Tax: She pays 40% on the £250 (£100).
• Lost Allowance: The £250 extra income reduces her tax-free allowance by £125. This £125 is now taxed at 40%, costing her another £50.
• National Insurance: She also pays 2% NI on the £250 (£5).

Total Deductions: £100 (Income Tax) + £50 (Lost Allowance Tax) + £5 (NI) = £155. Take-home Pay: £250 - £155 = £95.

Anna effectively keeps only 38% of her extra earnings. This is often called the "60% tax trap" because the effective Income Tax rate is 60% (40% standard rate + 20% from the lost allowance). When you add the 2% National Insurance, the total marginal deduction rate hits 62%.

For £95, she has to stay home, monitor dashboards, and potentially wake up at midnight, missing out on plans with friends and family. She still earns the extra money. But is it worth it?

Take-Home Pay Calculator: Is Extra Income Above £100k Worth It?

You also have a Personal Savings Allowance. This means you don't have to pay tax on the interest earned in your saving accounts up to a certain limit:

• Basic Rate Payers: First £1,000 of interest is tax-free.
• Higher Rate Payers: First £500 of interest is tax-free.
• Additional Rate Payers: No savings allowance (0%).

If you exceed these limits, your bank usually reports this to HMRC, and your tax code might be adjusted. To protect your money from unnecessary taxation, many expats choose to use tax "wrappers" such as an ISA. You can learn more about shielding your wealth in my guide to UK investments.

Hidden "Taxes": Child Benefit and Student Loans

When planning your budget, especially if you are renting a flat in London, you must account for two other significant deductions that act like income tax.

The High Income Child Benefit Charge (HICBC)

If you or your partner earn over £60,000, you begin to lose your Child Benefit. For every £160 you earn above £60k, you must pay back 1% of the benefit. By the time you reach £80,000, you have effectively paid back the entire amount. This can feel like a massive tax hike for families in that specific income bracket.

Student Loan Repayments

If you have a UK student loan (or a foreign one being collected via PAYE), these repayments are deducted from your gross pay. For most modern plans, you pay 9% on everything you earn over a certain threshold (around £27k). Because this is taken alongside tax and NI, a basic rate payer can feel like they are being taxed at 31% (20% tax + 2% NI + 9% loan) on their marginal income.

How UK Income Tax Is Calculated: Step-by-Step Examples

Let’s say you earn £30000 a year (your total gross income), your tax code is default 1257L which means you don’t pay tax on first £12570 pounds. You have to pay a 20% tax only on the slice of 30000-12570=17430 - this is what HMRC would call a taxable income. 20% on this sum is £3485.8.

Example for earning £80000

If you earn £80000 a year (your total gross income), your tax calculations are the following:

• the first £12570 --------------------------------------- no tax
• (£50270-£12570) = £37700 ------------------------------- 20%
• whatever is above £50270: £80000-£50270 = £29730 --------- 40%

In total, your tax liability on £80000 earnings are:

0 + (37700 * 0.2) + (29730 * 0.4)

0 + 7539.8 + 11892 = 19432

This is how much income tax you pay in a year. This is not your net income yet, as you still have to pay NI - national insurance.

National Insurance Contributions (NIC): What You Pay and Why

National Insurance is paid separately from income tax. It is calculated on your gross salary, and it does not reduce your taxable income for income tax purposes.

What Does a Tax Code Change Mean for Your Payslip?

Changes to your tax code meaning changes to your tax free personal allowance. Let’s say, you had earned some additional income apart from your main employment in the previous year (might be % on savings you earned). HMRC needs to collect tax on that. Let’s say they calculated you owe them 234 pounds. One way they can collect a tax is by reducing your tax free allowance and changing your tax code. What often happens is that you receive a letter that says that your tax code is changing from 1257L to 1140T. It means that in your case, now 20% tax applies starting at 11400 pounds, so you’ll have to pay an 20% of that. Calculations: (12570-11400)*0.2 = 234 extra in tax.

How to Legally Reduce Your UK Tax Bill

If you find yourself drifting into the 40% or 60% tax zones, there are three primary ways to keep more of your hard-earned money:

1. Pension Contributions: This is the most powerful tool. Money put into a pension is taken from your "top" slice of income before tax is applied. If you put £1,000 into a pension, it might only cost you £600 (if you're a 40% payer) or even just £400 in the 60% trap. To learn more about how this works, check out my UK Pension Guide (Part 1) and Advanced Pension Strategy (Part 2).
2. Salary Sacrifice: Some employers offer schemes for electric cars, cycles to work, or gym memberships where the cost is deducted from your gross pay before tax.
3. Gift Aid: Donating to charity via Gift Aid allows the charity to claim back the basic rate tax. If you are a higher-rate payer, you can also claim back the difference between the basic and higher rate for yourself via a Self-Assessment tax return.

Understanding how tax works in the UK takes time, especially when terms like “personal allowance”, “tax code”, and “National Insurance” all overlap. However, once you know how the pieces fit together, reading your payslip becomes satisfying rather than confusing.

Whether you’re earning £30k or approaching the higher tax bands, the key is awareness. If you have any remaining questions about the local financial landscape, check out my guide on opening a UK bank account to ensure your foundation is solid.

Final Tip: Check your Personal Tax Account in HMRC app. It is the most reliable way to ensure HMRC has the right information about your income and that you aren't overpaying.