A £100,000 salary is often celebrated as a milestone — but in the UK, it also triggers a specific set of tax traps that can make the effective cost of earning between £100,000 and £125,140 feel punishing. This guide explains what’s happening and what to do about it, in priority order.
Your Profile at £100,000
| Situation | |
|---|---|
| Gross income | £100,000 (salary, bonus, or consultancy) |
| Income tax (standard rate) | ~£33,000/year |
| Effective marginal rate (£100k–£125,140) | 60% |
| Personal allowance | £12,570 (but tapered away above £100k) |
| Take-home (without planning) | ~£67,000/year (~£5,583/month) |
| Key risks | PA taper, childcare cliff, pension under-funding |
Understanding the 60% Marginal Rate Trap
The personal allowance is £12,570 in 2026/27. It starts being withdrawn at £100,000 — £1 lost for every £2 earned above £100,000. At £125,140, it is fully gone.
Effective marginal rate in the taper zone:
- 40% income tax (higher rate band)
- +20% effective rate from PA withdrawal (the lost PA is taxed at 20%)
- = 60% effective marginal rate on every £1 earned between £100,000 and £125,140
On a salary of £110,000: the £10,000 above £100,000 costs you £6,000 in income tax + £2,000 in lost PA tax = £8,000 in tax. You keep £2,000 of that £10,000. The marginal rate is 80% on this slice — not 60%.
Wait — let’s be precise. Between £100,000 and £125,140 (the PA withdrawal zone), the rate is 60%. Above £125,140, it returns to 45%.
Priority 1 — Pension Contributions to Restore the Personal Allowance
The most powerful single action at £100,000+ income: make pension contributions that reduce your adjusted net income below £100,000.
Adjusted net income = gross income minus personal pension contributions (or company pension contributions via salary sacrifice).
Example at £110,000:
- Without action: lose £5,000 of personal allowance → pay extra £2,000 in tax (20% on £10,000 lost PA)
- Pension contribution: £10,000
- Adjusted net income: £100,000
- Personal allowance restored: £12,570
- Tax saving: ~£4,000 (40% higher rate relief + PA restoration)
- Net cost of £10,000 pension contribution: £6,000 in take-home
This £10,000 pension contribution costs you £6,000 and builds £10,000 of retirement wealth. It effectively pays 67% of itself through tax savings.
Salary sacrifice: If your employer offers salary sacrifice pension contributions, these reduce gross income before tax and NI — even more efficient than personal contributions.
Priority 2 — Tax-Free Childcare and 30 Hours — The £100,000 Cliff
If you have children under 12, you may be losing:
- 30 hours funded childcare (3–4 year olds): worth £5,000–£7,000/year
- Tax-Free Childcare: up to £2,000/year per child government contribution
Both are withdrawn if either parent earns above £100,000 (adjusted net income).
Strategy: A pension contribution that reduces your adjusted net income to £99,999 restores both. On a £108,000 salary with two children under 5:
- Pension contribution needed: £8,001
- Restored benefits: £5,000 (30 hours childcare) + £4,000 (Tax-Free Childcare for 2 children) = £9,000
- The pension contribution of £8,001 (costing you ~£4,800 after tax relief) saves £9,000 in benefits
- Net financial gain: approximately £4,200 — the pension contribution makes money
Priority 3 — ISA Contributions for Flexibility
Pension contributions are powerful but illiquid until 57. ISA contributions (up to £20,000/year) provide:
- Tax-free growth and withdrawals
- No access restrictions
- Estate planning flexibility (ISA passes to spouse via APS)
- Useful for medium-term goals (school fees, career change, early retirement)
At £100,000, maximise pension first (to restore PA), then ISA with remaining surplus.
Priority 4 — Child Benefit (High Income Charge)
Child Benefit pays £25.60/week for the first child and £16.95 for each subsequent child (2026/27). If your adjusted net income exceeds £60,000, you repay the benefit through the High Income Child Benefit Charge — the charge is gradual (1% of benefit per £200 over £60,000).
At £80,000, the full Child Benefit is clawed back. But at £100,000, pension contributions that bring adjusted net income below £60,000 can restore Child Benefit — a significant additional saving.
For two children at £100,000:
- Annual Child Benefit: £1,332 + £881 = £2,213/year
- Pension contribution to recover: £40,000 of income must be offset
- Not achievable in most cases by pension alone at this income level
Check whether you are claiming Child Benefit at all — even if you’ll pay the charge, it’s worth claiming and repaying rather than not claiming (avoids NI record gaps if not working).
Priority 5 — Inheritance Tax Planning
At £100,000 salary, a working lifetime of savings typically produces an estate well above the IHT threshold. Key actions:
| Action | IHT benefit |
|---|---|
| Pension maximisation (until April 2027) | Pension outside estate |
| Annual gift exemption (£3,000/year) | Immediately outside estate |
| Life insurance in trust | Payout outside estate |
| ISA → held to death → passes to spouse | Tax-efficient via APS |
From April 2027: Pension pots will be included in estates. This significantly changes planning for high earners who have been using pensions as estate-planning vehicles. Review your estate position in 2026/27.
Your Take-Home at £100,000 — With and Without Planning
| Scenario | Annual take-home |
|---|---|
| No pension contribution | ~£67,000 (~£5,583/month) |
| £10,000 pension contribution | ~£63,400 (~£5,283/month) + £10,000 pension |
| £25,140 pension (removes taper entirely) | ~£56,100 (~£4,675/month) + £25,140 pension |
The third scenario — contributing £25,140 to fully exit the taper zone — costs £10,900 in take-home but adds £25,140 in pension. Net cost: £10,900. This is an outstanding return on a pension contribution.