Introduction
For millions of people, Income Tax is one of the first taxes they encounter.
The moment someone starts their first job, they may notice that part of their wages has been deducted before it reaches their bank account. A payslip often contains unfamiliar terms such as Income Tax, PAYE and National Insurance, leaving many people wondering where some of their earnings have gone.
Yet despite paying Income Tax for much of their working lives, many people are unsure how it actually works.
Some believe that earning just a little more could push them into a higher tax band and leave them worse off. Others think that everyone pays the same rate of Income Tax or that pensioners never pay it.
These are common misunderstandings, but the reality is much simpler.
In the previous chapter, we explored why governments collect taxes and how taxation helps fund the public services on which modern society depends. We also saw that the UK uses a variety of different taxes because no single tax could raise enough revenue on its own.
Income Tax is one of the most important of these taxes.
It raises hundreds of billions of pounds each year and provides a significant proportion of the money used to fund services such as the NHS, education, defence, policing and many other areas of public spending.
This chapter explains what Income Tax is, who pays it, how tax bands work and why the system is designed in the way it is. By the end, you should be able to read a payslip with much greater confidence and understand one of the most important sources of government revenue.
The One Big Idea
Income Tax is a progressive tax on personal income.
This means that people generally pay tax only on the part of their income that exceeds a tax-free allowance, and higher rates of tax apply only to higher portions of income.
The aim is to raise money for public services while asking people with higher incomes to contribute a larger share of their earnings.
Understanding this one principle makes almost every other part of the Income Tax system much easier to understand.
What Is Income Tax?
Income Tax is a tax charged on many forms of personal income.
For most people, this means tax on the money they earn from work, but Income Tax can also apply to other types of income depending on the circumstances.
Examples include:
- earnings from employment;
- profits from self-employment;
- pension income;
- rental income from property; and
- some forms of investment income.
The detailed rules differ for each type of income, and there are various allowances and exemptions that apply in different situations. However, the basic principle remains the same.
When people earn income above certain thresholds set by the government, part of that income may be taxed.
The amount of tax someone pays depends on several factors, including how much they earn and the rules that apply during that tax year.
Unlike some other taxes, Income Tax is based on income, not spending.
If you decide to buy a new television, you may pay VAT because you are spending money.
If you receive wages from your employer, Income Tax may be deducted because you are earning money.
This distinction between taxing income and taxing spending is one of the reasons the UK has several different taxes rather than relying on just one.
Why Do Governments Tax Income?
As we learned in How Taxes Work, governments collect taxes to fund public services and carry out the many responsibilities expected of a modern state.
Income Tax is one of the largest and most reliable sources of this revenue.
The money collected helps pay for services such as:
- the NHS;
- schools and universities;
- policing and the justice system;
- the armed forces;
- transport infrastructure;
- welfare and pensions;
- local government services; and
- many other areas of public spending.
One reason Income Tax plays such an important role is that employment provides the main source of income for millions of people.
Because earnings are generally linked to a person’s ability to contribute financially, many countries use Income Tax as one of the principal ways of raising government revenue.
Income Tax also grows alongside the economy.
When more people are in work, wages increase or businesses become more successful, governments often collect more Income Tax without introducing new taxes.
Conversely, during periods of economic slowdown, Income Tax receipts may fall as employment or earnings decline. This is one reason governments rely on a variety of different taxes rather than depending entirely on Income Tax alone.
Income Tax is therefore not simply a tax on earnings.
It is one of the foundations of the UK’s system of public finance, helping to provide the resources needed to fund many of the services on which society depends.
Who Pays Income Tax?
A common misunderstanding is that everyone who earns money automatically pays Income Tax.
In reality, that is not the case.
Most people are allowed to earn a certain amount each tax year before they begin paying Income Tax. This tax-free amount is known as the Personal Allowance, and we will look at it in the next section.
Whether someone pays Income Tax depends primarily on how much taxable income they receive, not on their age or occupation.
For example:
- employees may pay Income Tax if their earnings exceed the Personal Allowance;
- self-employed people may also pay Income Tax on their profits;
- pensioners can pay Income Tax if their taxable income is high enough; and
- students who earn enough through part-time or full-time work may also become liable for Income Tax.
In other words, Income Tax is based on income rather than whether someone is a student, retired or employed in a particular profession.
Once a person’s taxable income rises above the Personal Allowance, part of that income may become subject to Income Tax according to the tax bands set by the government.
The next section explains how the Personal Allowance works and why it is one of the most important features of the UK’s Income Tax system.
The Personal Allowance
One of the most important features of the UK’s Income Tax system is the Personal Allowance.
The Personal Allowance is the amount of taxable income that most people can earn each tax year before they begin paying Income Tax.
This means that Income Tax is not charged on every pound that someone earns.
Instead, most people can earn a certain amount tax-free, with Income Tax only applying to income above that allowance.
The government normally reviews the Personal Allowance each year as part of the Budget, and the amount can change over time. For that reason, it is more useful to understand the principle than to memorise a particular figure.
For example, imagine that the Personal Allowance is £X.
- Someone earning less than £X would normally pay no Income Tax.
- Someone earning slightly more than £X would pay Income Tax only on the amount above the allowance.
This distinction is important because many people mistakenly believe that once they cross the threshold, all of their income becomes taxable.
That is not how the system works.
Only the income above the Personal Allowance becomes liable for Income Tax.
This approach reflects the idea that people should normally be able to earn a basic level of income before paying tax.
How Tax Bands Work
After the Personal Allowance, Income Tax is charged using tax bands.
This is one of the areas that many people find confusing, but the underlying idea is actually quite straightforward.
Rather than taxing all of someone’s income at a single rate, the UK divides taxable income into different bands.
Each band has its own tax rate.
As a person’s income increases, they may move into higher tax bands.
However—and this is one of the most important things to understand—only the part of their income that falls within a higher band is taxed at the higher rate.
The rest of their income continues to be taxed at the lower rates that apply to the earlier bands.
This is why Income Tax is described as a progressive tax.
Higher rates apply progressively to higher portions of income rather than to all of a person’s earnings.
A Simple Example
Imagine a staircase.
Each step represents a different tax band.
You begin on the first step, where your income is covered by the Personal Allowance.
As your income grows, you move up the staircase.
Each new step has a different tax rate.
The important point is that stepping onto the next step does not change the tax paid on the steps below.
Only the income on the new step is taxed at the higher rate.
This staircase analogy explains why moving into a higher tax band does not suddenly increase the tax on everything you earn.
Why a Pay Rise Does Not Leave You Worse Off
A common myth is that receiving a pay rise can leave someone with less money because they move into a higher tax band.
In almost every normal situation, this is not true.
Suppose someone receives a salary increase that moves a small part of their income into the next tax band.
Only that additional part of their earnings is taxed at the higher rate.
Everything below the threshold continues to be taxed exactly as before.
Although they may pay a little more tax on the extra income, they will almost always take home more money overallthan they did before the pay rise.
This is one of the most persistent misunderstandings about Income Tax, and understanding tax bands helps explain why it is incorrect.
Marginal Tax Rates and Average Tax Rates
This brings us to another idea that often causes confusion.
People sometimes say things like:
“I’m a 40% taxpayer.”
This statement is often misunderstood.
In most cases, it does not mean that 40% of all their income goes to the government.
Instead, it usually means that the highest part of their taxable income falls into the 40% tax band.
Economists describe this as the marginal tax rate.
The marginal tax rate is the rate of tax paid on the next pound of taxable income.
By contrast, the average tax rate is the proportion of a person’s total income that is paid in Income Tax overall.
Because the Personal Allowance and lower tax bands are applied first, a person’s average tax rate is usually much lower than their highest marginal tax rate.
For example, someone whose highest tax band is 40% may still pay an average Income Tax rate that is considerably lower because much of their income has either been tax-free or taxed at lower rates.
Understanding the difference between marginal and average tax rates makes many discussions about Income Tax much easier to follow.
It also explains why headlines referring to “higher-rate taxpayers” do not mean that all of those taxpayers pay the higher rate on all of their income.
How Income Tax Is Collected
Most people do not have to calculate and send their Income Tax to the government themselves.
Instead, much of the system operates automatically.
There are two main ways Income Tax is collected.
Pay As You Earn (PAYE)
For most employees, Income Tax is collected through a system called Pay As You Earn (PAYE).
Under PAYE, employers calculate how much Income Tax should be deducted from each employee’s wages before they are paid.
The employer then sends that money directly to HM Revenue & Customs (HMRC) on the employee’s behalf.
As a result, most employees never need to make separate Income Tax payments because the tax has already been deducted before their salary reaches their bank account.
This is why the amount shown on a payslip is often lower than the employee’s gross salary.
Self Assessment
Not everyone is paid through PAYE.
Many self-employed people, landlords and others with more complex financial arrangements use a system known as Self Assessment.
Under this system, individuals calculate their taxable income, complete a tax return and pay any Income Tax they owe directly to HMRC.
Although this requires more responsibility than PAYE, the underlying principles of Income Tax remain exactly the same.
The difference is simply how the tax is collected, not how the tax works.
Understanding these two collection methods helps explain why different people interact with the tax system in different ways, even though they are all contributing to the same overall system of public finance.
Why Is Income Tax Progressive?
One of the defining features of the UK’s Income Tax system is that it is progressive.
A progressive tax is one in which people with higher incomes generally pay a larger proportion of their income in tax than those with lower incomes.
As we have already seen, this does not mean that all of a person’s income is taxed at the highest rate. Instead, higher tax rates apply only to the portions of income that fall within the higher tax bands.
Many countries use progressive income taxes because they believe that people’s ability to contribute increases as their income rises.
To understand this idea, imagine two people.
One earns £25,000 a year.
The other earns £250,000 a year.
Both need to pay for essentials such as housing, food, heating and transport.
Although these costs may differ from one household to another, they usually make up a much larger proportion of the first person’s income than the second’s.
Supporters of progressive taxation argue that asking higher earners to contribute a larger share of their income still leaves them with a greater ability to meet their living costs than someone on a much lower income.
Critics, however, argue that higher tax rates may reduce incentives to work, save, invest or start businesses.
As with many topics in economics, there is no single answer that everyone agrees upon.
What is important for now is simply understanding how the system works.
Whether a progressive tax system is the fairest approach is a question we will return to later in Fair Society, when we explore ideas such as fairness, equality of opportunity and different approaches to taxation.
Why Do People Disagree About Income Tax?
Few areas of public policy generate as much discussion as Income Tax.
Almost everyone agrees that governments need tax revenue to fund public services.
Where opinions differ is over how much tax should be collected and how it should be shared between different taxpayers.
Some people argue that higher earners should contribute a larger share because they have a greater ability to pay and because this provides more funding for public services.
Others argue that lower tax rates encourage people to work, invest, take entrepreneurial risks and grow the economy, ultimately benefiting society as a whole.
There are also debates about where tax thresholds should be set, how generous the Personal Allowance should be and whether different forms of income should be taxed in different ways.
These debates often involve balancing several competing objectives.
Governments want to raise enough money to fund public services.
At the same time, they usually want to encourage employment, investment and economic growth.
They also want the tax system to be seen as fair by the public.
Achieving all of these aims simultaneously is challenging, which is why Income Tax continues to be one of the most debated parts of the UK’s tax system.
The purpose of this chapter is not to decide which approach is best.
Instead, it is to provide the knowledge needed to understand these debates when they arise.
Why Income Tax Matters
For many people, Income Tax is the single largest tax they will pay during their lifetime.
It is also one of the largest sources of government revenue, helping to fund many of the public services that people use every day.
Understanding Income Tax has practical benefits as well.
It helps people:
- understand their payslips;
- make sense of tax codes and tax bands;
- understand announcements made in the Budget;
- evaluate political proposals about taxation; and
- make better-informed financial decisions throughout their lives.
More broadly, Income Tax illustrates an important principle that runs throughout Fair Society.
Modern societies depend upon people contributing towards services that benefit everyone.
Exactly how those contributions should be shared is one of the central questions in economics, politics and philosophy.
By understanding how Income Tax works today, readers will be better prepared to explore those wider questions in later sections of the website.
Looking at Income Tax in Context
Income Tax is only one part of the UK’s overall tax system.
In the previous chapter, we saw that governments use a variety of different taxes rather than relying on a single source of revenue.
Each tax has its own purpose.
Income Tax is primarily linked to earnings.
Other taxes are linked to spending, business profits, property or particular goods and services.
Together, these taxes provide the revenue that allows the government to prepare its Budget, fund public services and respond to future challenges.
Understanding Income Tax therefore helps explain one important part of the picture, but it is only one chapter in the story of how the UK’s public finances work.
The next chapter explores another deduction that appears on millions of payslips each month:
National Insurance.
Although it is often collected alongside Income Tax, it has a different history, a different purpose and its own set of rules. Understanding the differences between the two is an important step in understanding the UK tax system as a whole.
Common Misunderstandings
Income Tax is one of the most familiar taxes in the UK, yet it is also one of the most misunderstood.
Many misconceptions arise because people hear terms such as tax bands, higher-rate taxpayer or 40% tax without fully understanding what they mean.
Let’s look at some of the most common misunderstandings.
“A Pay Rise Could Leave Me Worse Off”
This is probably the most widespread myth about Income Tax.
Many people worry that earning a little more money could push them into a higher tax band and leave them with less money overall.
In almost every normal situation, this is not true.
If part of your income moves into a higher tax band, only that additional part is taxed at the higher rate.
The rest of your income continues to be taxed exactly as before.
As a result, a pay rise almost always means you take home more money, even though you may pay a little more tax on the extra earnings.
Understanding marginal tax rates helps explain why this common belief is incorrect.
“Higher-Rate Taxpayers Pay the Higher Rate on All Their Income”
Another common misunderstanding is that someone who becomes a higher-rate taxpayer suddenly pays the higher rate on every pound they earn.
That is not how the UK Income Tax system works.
Income is taxed in stages.
The Personal Allowance applies first.
Then the lower tax bands apply.
Only the part of income that falls into a higher band is taxed at the higher rate.
For this reason, someone whose highest marginal tax rate is 40% usually pays a much lower average rate of Income Tax across all of their income.
“Everyone Pays Income Tax”
Not everyone pays Income Tax.
Most people can earn up to the Personal Allowance before Income Tax becomes payable.
Someone with income below that allowance will normally pay no Income Tax, although they may still pay other taxes such as VAT or Fuel Duty.
This illustrates an important point we saw in the previous chapter:
Almost everyone contributes to government revenue in some way, but not everyone pays the same taxes.
“Pensioners Don’t Pay Income Tax”
People sometimes assume that retirement automatically means they stop paying Income Tax.
In reality, Income Tax depends on taxable income, not age.
Someone receiving a pension, rental income or other taxable income above the Personal Allowance may still pay Income Tax.
Whether someone pays depends on the amount and type of income they receive, rather than whether they are working or retired.
“Income Tax and National Insurance Are the Same Thing”
Income Tax and National Insurance often appear together on a payslip, which leads many people to think they are simply two names for the same deduction.
They are not.
Although both are usually deducted from earnings, they have different histories, different rules and different purposes.
Income Tax is one of the government’s largest general sources of revenue.
National Insurance began as a system of social insurance and continues to play a different role within the UK’s public finances.
The next chapter explains these differences in detail.
Conclusion
Income Tax is one of the foundations of the UK’s public finances.
It provides a substantial proportion of the money that funds public services and allows the government to carry out many of its responsibilities.
Although the rules may appear complicated at first, the underlying principles are relatively straightforward.
Most people can earn a certain amount before paying Income Tax.
After that, only the income above the Personal Allowance is taxed, with higher tax rates applying progressively to higher portions of income.
Understanding these principles makes it much easier to read a payslip, understand announcements in the Budget and follow public debates about taxation.
It also demonstrates an important theme that runs throughout Fair Society.
Public finance is not simply about collecting money.
It is about deciding how society shares the cost of the services and institutions on which we all depend.
Exactly how those contributions should be shared is one of the biggest questions in economics, politics and philosophy, and one we will continue to explore throughout this learning journey.
Continue Learning
You now understand how the UK’s largest personal tax works.
You have learned:
- what Income Tax is;
- who pays it;
- how the Personal Allowance works;
- how tax bands operate;
- the difference between marginal and average tax rates;
- how Income Tax is collected; and
- why Income Tax remains one of the most important and widely debated taxes in the UK.
However, if you look at a typical payslip, you’ll usually notice another deduction alongside Income Tax:
National Insurance.
Although it is also based on earnings, National Insurance has a different history, different rules and a different purpose.
In the next chapter, National Insurance Explained, we’ll explore why it exists, how it is calculated and how it fits into the UK’s wider system of taxation and public finance.
Together, Income Tax and National Insurance form the two deductions that most employees encounter throughout their working lives. Understanding both provides a much clearer picture of how the UK raises a significant proportion of the revenue that funds public services and supports modern society.