Income Tax is the deduction most people have opinions about, usually strong ones, but relatively few people could explain exactly how it's collected, where the money actually goes, or whether the system is as harsh on higher earners as it sometimes feels. This guide covers all three, starting with the mechanism itself.

For how Income Tax affects your specific take-home pay, use our take-home pay calculator, which works it out automatically alongside National Insurance and any pension or student loan deductions.

What PAYE Actually Is

PAYE stands for Pay As You Earn, and it's not a tax in itself, it's the collection system Income Tax runs through for most employees. Rather than paying a lump sum once a year, your employer calculates what you owe each time you're paid, deducts it automatically, and sends it straight to HMRC on your behalf.

It was introduced in 1944, replacing a system where tax was assessed and paid well after the income had already been earned and, often, spent. Collecting tax in real time as people were actually paid solved a genuine administrative problem, both for the government's cash flow and for taxpayers who previously faced large, delayed bills.

The practical effect is that most employees never really "pay" their Income Tax in the way they might think of paying a bill. It's calculated and removed before the money reaches your bank account, based on your tax code, which tells your employer how much of your income should be tax-free. If you're self-employed, none of this applies. You calculate and pay your own Income Tax through Self Assessment instead, usually in arrears, which is a meaningfully different experience and one of the real practical differences between employment and self-employment.

What Income Tax Actually Pays For

Income Tax doesn't go into a ringfenced pot for one specific purpose. It's pooled with other tax revenue and allocated across government spending as part of the annual budget process, so there's no direct line from "your Income Tax" to any particular service.

That said, it's genuinely useful to see the shape of where UK government spending goes overall, since Income Tax is one of the largest contributors to that pool. Roughly speaking, welfare and pensions together account for close to 30% of total government spending, health takes around a fifth, education around a tenth, and debt interest, paying the interest on money the government has previously borrowed, takes close to a tenth on its own. The remainder is spread across defence, policing, transport, housing, and every other department and public service.

Why Does It Feel Like So Much?

Part of the answer is a genuine, very common misunderstanding about how tax bands work, which you can see reflected directly in our take-home pay calculator, but it's worth restating here because it directly affects how "unfair" the system feels. Moving into the higher rate band doesn't mean your whole salary is suddenly taxed at 40%, only the portion that falls inside that band is. Your average tax rate, what you actually pay as a percentage of your total income, is always lower than your marginal rate, what you pay on your next pound earned. Confusing the two is probably the single biggest reason people overestimate how much tax they're really paying.

The other part of the answer is that the UK system is genuinely progressive, meaning higher earners pay a larger share of income tax, both in absolute terms and relative to their share of total income. HMRC data shows the top 1% of taxpayers earn around 13% of total income but pay around 28% of all Income Tax, more than double their share of income. The top 10% of taxpayers pay close to 58% of all Income Tax collected. Whether that balance feels right is a genuinely contested political question people reasonably disagree on, but the underlying fact isn't in dispute: the system is structured so that a relatively small number of high earners contribute a disproportionately large share of total revenue.

The 2026/27 Income Tax Bands

Everyone gets the same tax-free Personal Allowance first, currently £12,570, and it's been frozen since 2021 with current plans keeping it frozen until 2031. As wages rise with inflation but the allowance doesn't move, more people drift into higher bands over time without ever getting a "real" pay rise in their pocket. This effect, known as fiscal drag, is a quiet but significant driver of rising tax bills that has nothing to do with the headline rates changing at all.

Scotland sets its own Income Tax rates and bands, running six bands from 19% to 48% rather than the three-band system used in England, Wales and Northern Ireland. If you're a Scottish taxpayer, our calculator applies these automatically.

Worked Example: £55,000 Salary

Here's how Income Tax alone breaks down for someone earning £55,000 in England, before any pension contribution is factored in.

That works out at an average tax rate of about 17.1% across the whole £55,000, even though the marginal rate on the last pound earned is 40%. It's a useful example precisely because the gap between those two numbers, 17.1% versus 40%, is usually much bigger than people expect.

Here's how that gap looks across a range of salaries:

Notice that even at £120,000, well inside the 40% higher-rate band, the average rate is still under 30%. The marginal rate tells you what happens to your next payrise, not what you're actually losing to tax overall.

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Common Misunderstandings

The average-versus-marginal rate confusion covered above is by far the most common one, and it's worth restating because it colours how people feel about almost every pay rise or bonus. Moving into a higher band never means your existing income gets taxed at the new, higher rate, only the slice that falls inside that band does. It's also the reason behind a very specific, very common myth about overtime specifically, covered in full in our overtime tax guide.

It's also easy to assume PAYE means your tax is always correct. It usually is, but tax codes can be wrong, particularly after a job change, a period of unemployment, or taking on a second job, and an incorrect code can mean you're overpaying or underpaying without realising it. See our full tax codes explained guide for what every letter and number actually means, and what to check if yours looks wrong.

Finally, people sometimes assume Income Tax and National Insurance are really just one combined "tax" with two names. They're calculated separately, on different thresholds, and only one of them, National Insurance, builds entitlement to the State Pension, which is a meaningful practical difference beyond the accounting.

Why Is Income Tax Separate From National Insurance?

Short version: they were built for different original purposes, Income Tax for general government spending, National Insurance as a contributory scheme linked to specific entitlements like the State Pension, and while the line between them has blurred considerably over time, they're still calculated on separate thresholds and rates.

For the full picture, including what National Insurance actually buys you and why gaps in your NI record can matter more than most people realise, see our National Insurance explained guide.