Only the pounds above the threshold are taxed at the higher rate, never your whole salary. In 2026/27 the higher rate starts at £50,270 of pay in England, Wales and Northern Ireland, so a rise from £48,000 to £55,000 leaves you £4,377.88 a year better off. You cannot take home less by earning more through a band, though there is one stretch of income where you keep noticeably less of each extra pound.
Only the pounds above the line
Income tax is charged in slices. Your Personal Allowance is taxed at nothing, the next slice at 20%, and only the pay above £50,270 at 40% in England, Wales and Northern Ireland. Crossing the line does not re-tax anything below it. Scotland runs more bands, at different points, and the section below gives them.
So a rise of one pound over the threshold costs 40% of that one pound and nothing else. The belief that a higher band applies to your whole salary is the single most expensive misunderstanding in UK pay, because it makes people turn down work that would have paid them.
The same is true of the additional rate, which starts at £125,140 and charges 45% on the pay above it.
What a rise is actually worth
Take a rise from £48,000 to £55,000, which is £7,000 of gross pay.
Before the rise, the take-home pay is £38,080.08 a year. After it, £42,457.96. So £7,000 of extra salary has produced £4,377.88 of extra take-home pay, and at the new salary the next hundred pounds faces a combined rate of 42% once income tax and National Insurance are counted together.
That combined rate is the number worth knowing, because it is not the rate in the band's name. National Insurance is charged on each pay period on its own, so on a monthly payroll it falls from 8% to 2% on pay above £4,189 a month — £50,268 across a year of equal monthly pay, just below where the higher rate begins at £50,270. The two changes partly cancel out, so the step at the higher-rate threshold is smaller than most people expect.
The band where the allowance disappears
There is one stretch of income where a rise genuinely is treated harshly. Above £100,000 of adjusted net income, the Personal Allowance is reduced by one pound for every £2 over that line, until it has gone.
Losing allowance while paying the higher rate means each extra pound is taxed twice over: once directly, and once by exposing a pound that used to be tax-free. At £110,000 the Personal Allowance has fallen from £12,570 to £7,570, and the combined rate on the next pound is 62%. You keep £37.96 of the next hundred pounds.
The band runs from £100,000 to £125,140, where the allowance reaches nothing and the rate falls back. Above that point an extra pound is taxed less heavily than inside the band, which is the one place in the system where a higher salary faces a lower marginal rate.
Adjusted net income is not the same as your salary. It is broadly your income from all sources, less the gross amount of any pension contributions given relief at source and of any Gift Aid donations, which is why two people on the same salary can be at different points in the taper.
Scotland is a different ladder
Scottish taxpayers run through more bands, and they change at different points. The Scottish higher rate of 42% begins at £43,662 of pay, and there is an intermediate rate of 21% below it that the rest of the UK does not have.
National Insurance is not devolved, so it changes at the same points wherever you live. That mismatch is what makes the Scottish marginal rate move in a different pattern from the rest of the UK across the same salaries.
The taper above £100,000 applies to the Personal Allowance UK-wide, so the same stretch of sharply higher marginal rates exists in Scotland, at Scottish rates.
The other lines a rise can cross
Income tax bands are not the only thresholds in a payslip. A student loan repayment starts at the plan's threshold and rises with pay above it. A workplace pension based on qualifying earnings has its own lower and upper limits. A High Income Child Benefit Charge applies to higher earners at a level set separately from the tax bands.
Several of these thresholds are frozen rather than rising with prices, which is why pay rises pull more people over them each year. The freeze and the dates it runs to are recorded in our rules file with their source.
Marginal rate and effective rate are different numbers
Your marginal rate is what the next pound faces. Your effective rate is what your whole income has actually cost you, averaged across every band below it.
Almost every complaint about tax bands is a marginal rate mistaken for an effective one. A salary a little above the higher-rate threshold pays the higher rate on a handful of pounds and nothing like 40% overall.
Can a pay rise leave me worse off?
Not through income tax or National Insurance. Every band charges its rate only on the pay above its threshold, so more gross pay always means more take-home pay, even inside the taper.
Things outside the tax system can move in steps rather than slices. Benefits, childcare support and some employer schemes have cliff edges of their own, and those are the cases where a rise can genuinely leave a household with less. They are worth checking separately, because the tax calculation on this page cannot see them.
What people do about the sharp band
Pension contributions and Gift Aid donations reduce adjusted net income, which is the figure the taper is measured against, so they change where in the band you sit. Salary sacrifice reduces gross pay before any of it is worked out, which has the same effect by a different route and also reduces National Insurance.
Those are descriptions of how the rules work, not suggestions about what to do with your money. What any of them is worth to you depends on your whole position, and a regulated financial adviser is the person to ask about that.