Earning exactly £100,000 in the UK sounds like arriving. Six-figure salary. Higher-rate band well behind you. The money page finally makes sense.

And then payroll runs your first month at that number and the shortfall from where you thought you’d land is somewhere between “surprising” and “infuriating.” This guide is the honest version: what £100,000 gross actually gives you as take-home in 2024/25, what happens the millisecond you cross that line, and the single sacrifice figure that most sensible earners at this level end up choosing.

⚡ Just want the number? Run £100,000 through our £100k Trap Calculator — you’ll get your personal ANI, marginal rate, and exact escape sacrifice in about 10 seconds. Free, no signup.

The headline number: £100,000 gross → £66,647 net (2024/25, no pension)

ItemAmount
Gross salary£100,000
Personal Allowance£12,570 (full — you’re on the edge of the taper, not in it)
Income Tax£27,432
Employee NI (Class 1)£5,271
Student loan (Plan 2, if any)£6,138
Take-home, no loan£67,297
Take-home, Plan 2 loan£61,159
Effective tax rate32.7%

Both numbers are before pension. Assume standard tax code, England/Wales/NI (rest-of-UK), no other income, no bonus.

Right at £100,000 you still have the full Personal Allowance. That’s important — the taper starts on the next pound, not on this one. This is why “£100k” is such a magical psychological ceiling: earning £99,999 is almost £0 of tax difference from £100,000, but £101,000 is meaningfully worse than £100,000.

What actually happens the moment you cross £100,000

Three separate things kick in the second your Adjusted Net Income (ANI) exceeds £100,000. Most articles talk about just the first one.

1. The 60% marginal rate on the £100k–£125,140 slice

For every £2 you earn above £100,000 you lose £1 of Personal Allowance. That “lost” £1 was previously tax-free but is now taxed at 40%, so it costs you 20p on top of the 40p Income Tax you were already paying — a 60% marginal rate. Add 2p Employee NI (upper-band) and you’re paying 62p tax on every extra pound until you hit £125,140.

A £5,000 pay rise from £100k → £105k adds ~£1,900 to your take-home. That’s £3.66/hour before pension, commute or lost weekends.

2. Tax-Free Childcare disappears (£100k cliff)

Tax-Free Childcare (TFC) is a government top-up worth up to £2,000 per child per year (£4,000 for a disabled child). Eligibility is a hard cliff: if either parent has ANI over £100,000 for the current tax year, the whole household loses TFC for that quarter — no taper, no phase-out.

If you have two kids in nursery, going from £100,000 → £100,001 ANI can cost your family £4,000 in real vouchers. That’s an implied marginal rate on that £1 of over £400,000%. It’s the single sharpest cliff in the UK benefit system.

3. HICBC applies (already active from £60,000, but relevant here too)

High Income Child Benefit Charge (HICBC) tapers Child Benefit between £60,000 and £80,000 of ANI. At £100,000 the tax you owe equals the full Child Benefit — you’ve lost it completely. This one you’ve already been paying since £80,000, but it’s worth naming because sacrificing back to £99,500 doesn’t fix HICBC. You’d need to sacrifice down to £80k for HICBC recovery.

The £5,000 cliff you never see

If you’re at exactly £100,000, cross £1 over, and don’t take corrective action, here’s the combined cost picture:

LossYearly value
Extra Income Tax at 62%£0.62 per £1 over
Tax-Free Childcare (2 kids)up to £4,000
HICBC (if kids under 16)already gone (from £80k)
Marginal rate on £100k → £101k with 2 kids in nurseryEffectively over 400%

This is why £100,000 is not just “a big salary” but the single most consequential tax threshold in the UK code. Almost everyone in the £95,000–£130,000 bracket is a candidate for pension sacrifice back below £100,000, not because pensions are magic but because the alternative is voluntarily paying for tax and benefit losses that dwarf the raw salary math.

The smallest sacrifice that fixes it: £500

If you’re bang on £100,000 and want to stay eligible for TFC (and keep a buffer for bank interest / dividends / small pay rises that would tip you into the taper), the answer is sacrifice £500 into your workplace pension. That drops ANI to £99,500 — £500 below the taper start.

MoveAmount
Extra pension contribution£500
Reduction in take-home (higher-rate + NI)£210
Effective personal cost per £142p
Personal Allowance restored£0 (still full at £100k)
Tax + NI directly saved£290
Tax-Free Childcare preservedup to £2,000/child/year

If you have two kids in nursery, you just spent £500 to protect £4,000 of vouchers plus £290 of direct tax + NI. That’s an ~850% return on £500 before any market growth. There is no other move in UK personal finance that comes close at this level.

If you don’t have children, the direct tax saving is £290 on £500 sacrificed — a still-excellent 58% return before growth, plus you’ve built a taper buffer for the next pay rise / bonus / bank-interest year.

The £2,000 sacrifice — for people already a bit over

If your ANI is more like £101,500 (a £1,500 bonus, or bank interest, or dividends pushed you over), sacrificing £2,000 is usually the right move — it takes ANI back to £99,500 with the same £500 buffer.

MoveAmount
Sacrifice into pension£2,000
Reduction in take-home (62% marginal)£760
Extra into pension£2,000
PA restored (from £11,820 → £12,570)£750 restored allowance
Direct tax + NI saved£1,240
Tax-Free Childcare preservedup to £2,000/child/year

Personal cost 38p per £1 into pension. If you have kids, this is genuinely a category-defining lifetime-value move.

When you should NOT sacrifice at £100k

There are three legitimate reasons to take the cash instead:

  1. Cash cushion is thin. Emergency fund and short-term goals come first. Sacrifice is one-way; if you’re made redundant next quarter, you can’t get the cash back out of your pension.
  2. You’re leaving the UK. Overseas transfer complexity, potential LTA charge if the pot is large, and you’ll pay tax again on drawdown in your new country.
  3. You’re planning a mortgage this year. Lenders use gross salary. A £10k sacrifice can knock ~£40k off your borrowing limit at 4× multiple.

For most single-employer PAYE earners at £100k with kids and a stable balance sheet, “sacrifice back to £99,500” is not an optimisation — it’s the default correct move.

Do the maths on your exact £100k (not this generic one)

Your actual ANI depends on your pension type (salary sacrifice / net pay / relief-at-source), any bonus timing, RSU vests, bank interest, dividends, and Gift Aid. Two people both earning “£100k gross” can have wildly different ANI numbers.

FAQ

Is Adjusted Net Income the same as gross salary? No. ANI = gross salary − salary-sacrifice pension − relief-at-source grossed-up pension − Gift Aid grossed-up + taxable savings + taxable dividends. So £100k gross with a £5k salary-sacrifice pension is £95k ANI. £100k gross plus £2k in bank interest is £102k ANI.

Does the £100k threshold include employer bonus? Yes. Bonus is taxable in the year it’s paid. This is why bonus timing (deferring into next tax year, or converting to pension) is the most common strategic lever at £95k–£120k salaries.

What about Scottish taxpayers? Scotland has its own bands (21% intermediate, 42% higher, 45% advanced, 48% top). The £100k Personal Allowance taper is UK-wide and still applies. Scottish higher-rate taxpayers in the £100k–£125,140 zone hit an effective marginal rate of 69.5% — worse than the rest-of-UK 62%. Our Scottish take-home calculator shows the exact figure at your salary.

Can I sacrifice retrospectively after the tax year ends? Salary sacrifice must be arranged before pay is received. But a personal SIPP contribution (relief at source) made before 5 April counts against that tax year’s ANI via Self Assessment — this is the classic “March SIPP top-up” move used by contractors and consultants who see the £100k line in sight late in the year.

Does the taper reset if I go over one year and back under the next? Yes. ANI is assessed each tax year independently. There is no lookback — cross the line one year, sacrifice the next, and the second year is fine.