Ever looked at a job offer and thought:
“£100k sounds amazing… but what do I actually get each month?”
That gap between headline salary and reality is exactly why Know Your Pay exists. Because if you do not understand your pay, you cannot own your money.
Between Income Tax, National Insurance, student loans, pensions, bonuses and benefits, your take home pay in the UK can be a lot lower than you expect — especially once you move into higher tax bands. Our UK salary calculator is built to fix that. No fluff. No guesswork. Just clear numbers you can actually use.
What the Know Your Pay Calculator Shows You
In seconds, you get a full breakdown of your net salary in the UK, including:
- Your annual, monthly, weekly and daily take home pay
- A full Income Tax breakdown across the 20%, 40% and 45% bands
- Your National Insurance contributions
- Student loan repayments across all plans
- The impact of pension contributions on your net pay
- Exactly how much you save with salary sacrifice (tax AND NI)
- Your bonus month take home versus a normal month
- What happens if you sacrifice your entire bonus to pension
- The tax cost of company cars, private medical and other benefits
- Your Adjusted Net Income — the number HMRC actually uses
- Whether you qualify for 30 hours free childcare
- Exactly how much pension you need to get back under £100k
- A full side by side salary comparison including total compensation
Step 1: Enter Your Gross Salary
Start with your gross salary. That is your pay before tax. If your income varies, use your best annual estimate. You can enter it as an annual, monthly or weekly figure using the Frequency dropdown.
Step 2: Pick the Right Tax Year
Tax rules change every April in the UK. Choose:
- 2024/25 for past calculations
- 2025/26 for the previous year
- 2026/27 for the current year and planning ahead
Small changes in thresholds can make a real difference to your take home pay.
Step 3: Check Your Tax Code
The default is 1257L, which gives you the standard Personal Allowance of £12,570. If your code is different — because of benefits in kind, marriage allowance or previous underpayments — update it here and the calculation adjusts automatically.
👉 Not sure? Check your payslip or your HMRC online account.
Step 4: Add Your Bonus
If you receive an annual bonus, enter the amount and select which month it is paid in. This unlocks one of the most useful features of the calculator — the bonus month breakdown.
A lot of people are genuinely shocked by how little of their bonus they actually receive. That is because HMRC taxes your bonus at your marginal rate, not an average. The calculator shows you:
- Your normal month take home (salary only)
- Your bonus month take home (salary plus bonus, after tax and NI)
- Exactly how much of the bonus you keep, how much goes to income tax, and how much to NI
💡 Example: on a £100,000 salary with a £20,000 December bonus, the bonus month take home is £13,313 — not £20,000 more than a normal month. The difference is £12,400 in tax and NI.
Step 5: Add Your Pension
This is where you start to own your money 💰. Enter your pension contribution as a percentage of salary (or as a fixed amount). The calculator handles two types of pension — and understanding the difference can make a real difference to your finances.
Regular pension contribution
Tax is calculated on your full salary, and your pension is deducted afterwards. You still get tax relief — the government tops up your contribution — but you do not save on National Insurance.
Salary sacrifice — saves tax AND NI
Enter your annual sacrifice amount in the Salary Sacrifice section. Unlike a regular pension contribution, salary sacrifice reduces your gross pay before tax and NI are both calculated. A green savings pill appears instantly showing exactly how much you save — split between tax saved and NI saved.
💰 Tip: Between £100,000 and £125,140, your effective tax rate is around 60%. Pension contributions and salary sacrifice in this range are extremely efficient — every pound in reduces your tax bill by 60p.
💡 Try increasing your pension from 5% to 10% and see how little your take home changes compared to how much goes into your pension.
Sacrifice all of bonus to pension
This is a game changer for higher earners. Tick “Sacrifice all of bonus to pension” and your entire bonus is redirected into your pension pot before tax or NI are calculated. You receive no cash bonus, but you pay nothing on it either.
The calculator shows you the total pension gain — including the tax and NI saved versus taking the bonus as cash. For a £20,000 bonus in the 60% taper zone, the effective pension gain can be over £32,000 compared to the £7,600 you would keep as cash. That is not a typo.
Step 6: Add Benefits in Kind
Got a company car, private medical insurance or an interest free loan? Enter the total benefit in kind value (from your P11D form) in the Taxable Benefits section.
Benefits in kind are taxed as salary — but importantly, you do not pay employee National Insurance on them. The calculator shows the exact extra income tax cost.
⚠️ Benefits in kind also add to your Adjusted Net Income. So a £5,000 private medical benefit on a £97,000 salary pushes your adjusted net income to £102,000 — into the personal allowance taper zone — even though your cash salary is below £100,000. The calculator flags this automatically.
Step 7: Select Your Student Loan Plan
Choose the correct plan:
- Plan 1 — started before September 2012
- Plan 2 — started from September 2012
- Plan 4 — Scottish students
- Plan 5 — started from 2023 onwards
- Postgraduate loan
Each plan has a different repayment threshold and rate. The deduction shows up as a separate line in the breakdown so you can see exactly what you are paying.
Step 8: Read the Breakdown
Most calculators give you one number. This shows you how it is built:
- Income taxed at 0% (your personal allowance)
- Income taxed at 20% (basic rate)
- Income taxed at 40% (higher rate)
- Income taxed at 45% (additional rate)
This is what helps you understand what actually happens when your salary changes — or when your bonus lands.
The £100k Trap and Why It Matters
If you remember one thing, make it this:
⚠️ £100,000 IS A CLIFF EDGE ⚠️
Go even £1 over and you can lose:
- 30 hours free childcare
- Tax free childcare
For many families, that is £7,000 to £15,000 or more each year.
The Key Number is Adjusted Net Income
HMRC does not look at your salary. It looks at your Adjusted Net Income — which includes your bonus and any benefit in kind, minus your pension contributions and salary sacrifice. Importantly, this is a number you can control. That is how you move from reacting to your income to actually managing it.
The Childcare Tab
If your income is anywhere near £100,000, switch to the Childcare tab. The calculator will:
- Calculate your Adjusted Net Income (including bonus and benefits)
- Show whether you currently qualify for 30 hours free childcare
- Tell you exactly how much extra pension or sacrifice you need to get back under £100,000
- Show the real monthly cost of that extra contribution after tax relief
Sacrificing an extra £5,000 into your pension might cost you as little as £250 per month after tax relief — but protect thousands of pounds of childcare benefit. The numbers often make the decision obvious.
The £100k Taper Tab
Switch to the £100k Taper tab to see the personal allowance taper in full detail. Between £100,000 and £125,140, you lose £1 of your £12,570 personal allowance for every £2 you earn — creating an effective 60% marginal rate on that slice.
The calculator shows:
- How much personal allowance you have left
- The extra tax you are paying because of the taper
- How much of the taper is caused by your bonus specifically
- Exactly how much extra pension or sacrifice escapes the zone entirely
If your salary alone is below £100,000 but your bonus pushes you over, the calculator flags this and tells you the exact sacrifice needed to bring your adjusted net income back down.
The Compare Tab: Should I Take the New Job?
The Compare tab is designed for one of the most common financial decisions people face — evaluating a job offer. Enter full details for both roles:
- Gross salary
- Annual bonus
- Your pension percentage and employer pension percentage
- Salary sacrifice and benefit in kind
- Whether to sacrifice the bonus to pension
The results show a total compensation banner at the top — gross salary plus bonus plus employer pension — so you can compare the full package, not just the headline number. Below it, every metric is shown side by side: income tax, NI, pension, net annual, net monthly, normal month take home, bonus month take home, and effective rates.
💡 A £110,000 role with no pension versus a £105,000 role with 8% employer pension can easily result in the lower salary role being worth more. The Compare tab makes this visible instantly.
3 Smart Ways to Use This Calculator
- Before a pay rise — a £10,000 increase does not always mean £10,000 more in your pocket. Know what it actually means first.
- Protect your childcare benefits — if you earn between £100k and £120k, the Childcare tab is essential. Run the numbers before you rule out extra pension contributions.
- Compare job offers properly — two salaries can look similar but feel very different once tax, deductions, employer pension and benefits are applied. Use the Compare tab every time.
A Few Things to Know
- Designed for UK employees
- Assumes relief at source pensions (enter salary sacrifice separately for the NI saving)
- The £100k childcare rule applies per parent — both must be under the threshold
- Benefit in kind values can be found on your P11D or tax code notice from HMRC
- The annual pension allowance tracker shows if you are approaching the £60,000 limit
The Bottom Line
Most people overestimate their take home pay and underestimate how much tax they pay. They also underestimate how powerful pensions and salary sacrifice can be — especially around the £100,000 threshold. At Know Your Pay, the goal is simple: help you understand your income so you can own your money.
