What is National Insurance and Why is My Pay Less Than Expected?

What is National Insurance and why is your pay less than expected? If you’ve just started your first job and your payslip has left you confused, you’re not alone.. Your first payslip arrives and the number is noticeably smaller than you expected. Before you’ve spent a single penny, a chunk has already gone.

One of the biggest reasons for that gap is National Insurance. Most people have heard of it. Far fewer actually understand what it is, why they pay it, or why it feels like yet another thing taking money before it even reaches them.

Here’s what you need to know.

What is National Insurance?

National Insurance (NI) is a tax on your earnings that funds certain state benefits – including the NHS, the State Pension, and things like Statutory Maternity Pay and Jobseeker’s Allowance.

It’s been around since 1911. It’s not optional. And it applies to almost everyone who works in the UK above a certain earnings threshold.

Think of it less as a deduction and more as a contribution – though it’s fair to say that distinction feels academic when you’re looking at a payslip and wondering where your money went.

How much National Insurance do I pay?

As an employee in the current tax year, you pay 8% National Insurance on earnings between £12,570 and £50,270 per year. Above £50,270 the rate drops to 2%.

You don’t pay anything on earnings below £12,570 – that’s the Primary Threshold.

So on a salary of £25,000, you’d pay National Insurance on roughly £12,430 of your earnings (the amount above the threshold). At 8%, that’s around £994 a year – or just over £82 a month coming out of your pay.

For the most up to date rates, you can check the current figures on gov.uk.

One thing worth knowing: NI is calculated per pay period, not annually. So if you receive a bonus in one month, you might pay more NI that month even if your overall annual earnings are below the threshold. It can be a surprise if you’re not expecting it – but it evens out over time.

What’s the difference between National Insurance and Income Tax?

They’re both deductions from your pay, but they’re separate things calculated differently.

Income Tax is based on your total taxable income and funds general government spending. You have a Personal Allowance of £12,570 before you start paying it – the same threshold as NI, which is why both kick in at a similar point.

National Insurance specifically funds social security benefits and your State Pension entitlement. Each year you pay NI counts as a qualifying year towards your State Pension. You need 35 qualifying years for the full amount.

So while both feel like money leaving your account, they’re doing different things. And your NI contributions are genuinely building something for your future – even if it feels a long way off right now.

Why does my employer pay National Insurance too?

Yes – your employer pays their own separate NI contribution on top of your salary. This is called Employer’s National Insurance and it’s currently 13.8% on earnings above the threshold.

You don’t see this on your payslip because it doesn’t come out of your pay – it’s an additional cost your employer pays on top of employing you. But it’s worth knowing about because it’s part of the real cost of having you on the payroll, which is relevant when you’re thinking about salary negotiations.

Why didn’t anyone explain this at school?

Honestly – that’s one of the questions I hear most often. And it’s a fair one.

Most people arrive at their first job having never seen a payslip before. They don’t know what NI is, why it exists, or how it’s calculated. They just know their take-home is less than they expected, and nobody has ever sat down and explained why.

That’s not a gap in your intelligence. It’s a gap in what we teach young people before they enter the world of work.

Understanding your payslip – really understanding it – changes how you budget, how you plan, and how confident you feel about your financial life. It’s one of the first things I go through with clients in a Single Session.

A quick summary of what comes out of your pay

To put it all together, here’s what typically comes out of a UK employee’s gross salary each month:

Income Tax – based on your earnings above the Personal Allowance (£12,570), at 20% for basic rate taxpayers.

National Insurance – 8% on earnings between £12,570 and £50,270.

Pension contributions – if you’re auto-enrolled, typically 5% of qualifying earnings from you, with at least 3% from your employer on top.

Everything else – your rent, your food, your life – comes out of what’s left. Which is why understanding the numbers before you budget matters so much.

The decision your payslip can’t make for you

Knowing what comes out is just the start. The real question is what you do with what’s left.

If you’d like help working out your actual take-home, building a budget that works for your life, or just getting a clear picture of where you stand financially – a Single Session is a good place to start. One hour, one clear picture, something concrete to take away.

Or come and join the conversation on the next Wednesday call – free, no pressure, just real talk about money and life. Request the Zoom link here.