Applies to: United Kingdom
A take-home calculator that gets three things right most of the field does not: it stacks an undergraduate student loan and a Postgraduate Loan together at 15%, it keeps Scottish rates off your savings and dividends, and it shows you the 60% band between £100,000 and £125,140.
If you did an undergraduate degree and then a masters, you probably hold two loans. They are separate debts with separate thresholds, and you repay both at the same time: 9% of everything above your undergraduate threshold, plus 6% of everything above £21,000, worked out independently and added together.
Above both thresholds that is a marginal rate of 15% before a penny of income tax or National Insurance. Most free calculators model a single plan and cannot stack them, so they report 9% and are six points out for everyone in this position.
| Plan | Threshold | Rate | Interest from 2026-09-01 | Written off |
|---|---|---|---|---|
| Plan 1 | £26,900 | 9% | 4.1% | twenty-five years, or age 65, depending on when the borrower started |
| Plan 2 | £29,385 | 9% | 6% | thirty years |
| Plan 4 | £33,795 | 9% | 4.1% | thirty years, or age 65, depending on when the borrower started |
| Plan 5 | £25,000 | 9% | 4.1% | forty years |
| Postgraduate Loan | £21,000 | 6% | 6% | thirty years |
Deductions are worked out per pay period, not across the year. Your employer looks at what you earned this month against a twelfth of the threshold. On a steady salary that comes to the same answer as an annual calculation. On an uneven one it does not: a single high month — a bonus, back pay, a month with three pay dates — triggers a deduction even if your income for the whole year is below the threshold and nothing was repayable at all. That money is not refunded automatically.
Scotland sets its own income tax rates and bands, and there are 6 of them against 3 in the rest of the UK. They apply to non-savings, non-dividend income only. Your savings interest and your dividends are taxed at the UK-wide rates set at Westminster, whatever your Scottish taxpayer status.
Several calculators apply the Scottish table to every kind of income. On a dividend that is wrong by up to nine percentage points, and in the wrong direction.
Scotland also cannot set the personal allowance — that is reserved — so the same £12,570 and the same £100,000 taper apply on both sides of the border.
| Band | Range | Rate |
|---|---|---|
| Rest of UK basic | £12,571 to £50,270 | 20% |
| Rest of UK higher | £50,271 to £125,140 | 40% |
| Rest of UK additional | over £125,140 | 45% |
| Scottish starter | £12,571 to £16,537 | 19% |
| Scottish basic | £16,538 to £29,526 | 20% |
| Scottish intermediate | £29,527 to £43,662 | 21% |
| Scottish higher | £43,663 to £75,000 | 42% |
| Scottish advanced | £75,001 to £125,140 | 45% |
| Scottish top | over £125,140 | 48% |
Wales is identical to England and Northern Ireland this year, and that is worth stating rather than assuming. The mechanism is that UK rates are cut by 10p for a Welsh taxpayer and the Senedd sets its own rate to add back; it has set 10p in every band every year since the power arrived. From 2027-04-06 the Senedd gains power to set separate rates on property income, which it has not yet used.
Between £100,000 and £125,140, the personal allowance is withdrawn at £1 of personal allowance lost for every £2 of adjusted net income above the threshold. Earn one more pound and you also lose fifty pence of allowance, so one pound fifty becomes taxable.
At the 40% higher rate that is an effective 60% on every pound in the band. In Scotland the same stretch of income falls inside the 45% advanced rate rather than the 40% higher rate, so it is about 67.5%.
A calculator with one “pension %” box is answering a question it has not asked. The three arrangements reduce different things:
Stage two of this page is the salary sacrifice interactions in full, including whether your employer passes on its own National Insurance saving — which changes what a sacrifice is worth by around fifteen percentage points.
Income tax rates rise as you earn more. National Insurance does the opposite at the top: 8% between the primary threshold and the upper earnings limit, then 2% above it. That is why your combined marginal rate drops at £50,270 before the 40% income tax band lifts it again.
| Band | Range | Rate |
|---|---|---|
| below the primary threshold | £0 to £12,570 | 0% |
| main | £12,571 to £50,270 | 8% |
| upper | over £50,270 | 2% |
Like the student loan, National Insurance is assessed on each pay period rather than across the year. The lower earnings limit of £123 a week is not a rate threshold: earning above it builds entitlement to the state pension and contributory benefits even though no contribution is due until £242 a week.
An average year is 365.25 days, which is 52.18 weeks and 26.089 fortnights. Fifty-two is close enough to look right and wrong enough to disagree with your payslip.
| Cycle | Pay dates a year | What most calculators use |
|---|---|---|
| Weekly | 52.18 | 52 |
| Fortnightly | 26.089 | 26 |
The whole-period assumption is offered above, labelled as what most calculators use, so if you are reconciling against another tool you can see where the two part company. It matters more here than it looks: student loan and National Insurance are both assessed per period, so the number of periods changes the answer rather than just the presentation.
Named rather than quietly left out, because a difference you cannot account for is one you will assume is somewhere else:
And PAYE will not match this exactly. Your employer works tax out from HMRC's tables per pay period rather than across the year, and those tables are rounded, so a small difference either way is normal and squares up over the year.
The assumptions this page does make: a full tax year on the same salary, no other employment, the standard tax code, and residence for tax purposes in the country you pick.