Written and reviewed by James Whitfield · Updated for 2025/26 · Editorial standards · Methodology
A plain-English guide to PAYE deductions and how gross salary becomes net monthly pay in the UK.
Use this guide to understand the exact path from gross salary to net monthly pay under PAYE. It is most useful when your payslip and online estimates do not match.
Most people start with one number: annual salary. But the figure HMRC taxes can be lower if you have pension salary sacrifice, and higher if you receive taxable benefits such as a company car or private medical cover. The key point is that your contract salary and your taxable income can diverge before a single calculation is done.
In a standard PAYE setup, your employer applies tax code allowances first, then calculates income tax across each relevant band. National Insurance is then calculated separately, with different thresholds and rates. This is why your payslip has multiple deduction lines rather than one combined tax figure.
When people ask why their net pay moved even though salary did not, the answer is usually in one of three places: tax code changes, pension contribution changes, or crossing a threshold where a higher marginal rate applies.
UK income tax is progressive — you pay different rates on different slices of income, not one flat rate on everything. For 2025/26, the personal allowance is £12,570 (taxed at 0%), then 20% on earnings from £12,571 to £50,270, then 40% on earnings from £50,271 to £125,140. Additional rate of 45% applies above £125,140.
A common misconception is that earning above the basic rate threshold means your whole salary is taxed at 40%. It does not. Only the slice above £50,270 moves to 40%. For example, on a £60,000 salary, the first £12,570 is tax-free, the next £37,700 is taxed at 20% (£7,540), and only the £9,730 above £50,270 is taxed at 40% (£3,892). Total income tax: £11,432.
Scottish residents use different bands set by the Scottish Parliament. Scotland has five income tax bands (starter, basic, intermediate, higher, top) with slightly different rates, which is why the same gross salary can produce a different take-home north of the border.
Employee National Insurance is calculated separately from income tax and uses different thresholds. For 2025/26, NI is charged at 8% on earnings between the primary threshold (£12,570/year) and the upper earnings limit (£50,270/year). Above £50,270, the rate drops to 2%. There is no NI on earnings below £12,570.
This means NI and income tax share the same lower threshold (£12,570) but diverge sharply at £50,270, where NI drops to 2% while income tax rises to 40%. At a salary of exactly £50,270, the marginal combined rate on the next pound of earnings shifts from 28% (20% IT + 8% NI) to 42% (40% IT + 2% NI).
Unlike income tax, NI is calculated monthly or weekly with no automatic annual reconciliation for most employees. This affects how bonuses and irregular payments are taxed — a large bonus in a single pay period can attract a higher NI rate on that payment even if the annual equivalent would not.
Student loan repayments are calculated as a percentage of income above a plan-specific threshold, not as a fixed amount. Plan 2 (the most common for graduates who started after 2012) charges 9% on income above £27,295 for 2025/26. On a £35,000 salary, that is 9% of £7,705 = £693 per year, or £57.75 per month — a deduction that basic calculators often ignore.
Pension contributions further reduce net pay. A 5% employee contribution on a £35,000 salary costs £1,750 gross per year, but if it is salary sacrifice, the real cost to your bank account is lower — approximately £1,260 per year after income tax and NI savings. The difference between salary sacrifice and standard contributions can be £490 per year on the same percentage.
For a realistic picture of monthly take-home, all four deductions need to be modelled together: income tax, NI, student loan, and pension. On a £35,000 salary with Plan 2 student loan and 5% salary sacrifice pension, monthly take-home drops from the headline £2,339 (tax and NI only) to approximately £2,223 — a £116/month difference that matters for rent affordability calculations.
If your estimate and payslip differ, check the fundamentals in order: tax code, region, student loan plan, pension setup and NI category. Most mismatches are explained by one of those fields rather than a calculation error.
Do this line-by-line rather than net-pay-only. Reconciliation is faster when you compare taxable pay, income tax and NI separately before checking net monthly output.
This calculator is suitable for role comparison, monthly budgeting and salary planning under known assumptions. It is not a substitute for payroll advice in edge-case tax situations.
If differences persist after input checks, use HMRC guidance and payroll support to confirm treatment for one-off adjustments, benefits or multi-employment scenarios.
Step 1: Determine taxable pay. Gross salary is £40,000. If salary sacrifice pension is 5% (£2,000), taxable pay drops to £38,000. The personal allowance (tax code 1257L = £12,570 allowance) is then subtracted. Taxable income = £38,000 − £12,570 = £25,430.
Step 2: Apply income tax. £25,430 falls entirely within the 20% basic-rate band (£0–£37,700 above allowance). Income tax = 20% × £25,430 = £5,086. No higher-rate tax applies because taxable income is below £37,700.
Step 3: Calculate employee NI. NI is not affected by salary sacrifice in a standard net-pay pension arrangement (though it is affected in salary sacrifice). For a £40,000 salary with standard net-pay pension: NIable pay = £40,000 − £12,570 (primary threshold) = £27,430, all within the 8% band. NI = 8% × £27,430 = £2,194. Step 4: Student loan. If Plan 2 applies, threshold is £27,295. Repayment = 9% × (£40,000 − £27,295) = 9% × £12,705 = £1,143/year. Step 5: Net annual pay = £40,000 − £2,000 (pension) − £5,086 (tax) − £2,194 (NI) − £1,143 (student loan) = £29,577. Monthly net ≈ £2,465.
PAYE is a cumulative system. Your employer applies the full year's tax and NI assumptions across each pay period, with adjustments made as the year progresses. In months 1–3, tax is applied on the assumption that your year-to-date pay is running at an annual rate. If a bonus is paid in month 4, PAYE treats the bonus as received in that month and applies marginal rates at that income level — which is why a bonus can create a temporarily higher tax deduction.
Tax code changes mid-year (for example, if HMRC adjusts your code to collect underpaid tax from the previous year) can also cause monthly variation. An emergency code (e.g. 1257L W1/M1, marked as non-cumulative) means your employer calculates each month in isolation without reference to year-to-date totals. This can result in overpayment of tax, which HMRC usually corrects via refund at year end or code adjustment.
The cleanest way to validate your payslip is to take a representative month in the middle of the tax year (say, October or November) and compare the year-to-date income tax figure against what you would expect on the same salary for 7 or 8 months. If the year-to-date tax is substantially higher or lower than expected, it usually indicates a tax-code issue or an earlier period where pay was irregular.
Current tax-year thresholds used across this guide and calculator.
PAYE applies income tax based on your tax code and tax bands, then employee National Insurance is calculated using separate NI thresholds. Student loan and pension deductions are then applied according to your selected plan and contribution setup. This order matters because each deduction has its own threshold and rate rules. When reconciling a payslip, compare each line item against the matching annual estimate instead of trying to infer everything from a single net figure.
Net pay can differ because of tax code differences, student loan plan type, pension contribution rate, salary sacrifice, and payroll timing. Two employees on the same headline salary may have materially different deductions if one has Plan 2 repayments and 5% pension while the other has no loan and no pension. The most reliable approach is to model your own setup directly, then compare that scenario to your current payslip settings.
Not always in real payroll. Calculators typically annualise first and then show monthly equivalents, while payroll systems process period-specific earnings and cumulative tax positions. That means small differences can appear in specific months, especially around bonus periods or tax code changes. Use annual estimates for planning and month-by-month payslips for reconciliation.
Yes. Use the scenario links in this guide to open prefilled states, then adjust salary, region, loan and pension settings.
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Tax region, tax code, student loan plan, pension contribution and salary sacrifice are the key assumptions to check first.