£100,000 is exactly at the threshold where the Personal Allowance taper begins. Take-home is approximately £67,557 per year — £5,630 per month. At this precise salary, the full Personal Allowance of £12,570 is still retained — but any income above this triggers the taper.
Between £100,000 and £125,140, the Personal Allowance is withdrawn at £1 for every £2 of income above the threshold. This creates an effective marginal rate of around 60% — far higher than the headline 40% or 45% rates. Pension contributions can restore the allowance.
| Item | Annual | Monthly |
|---|---|---|
| Gross salary | £100,000 | £8,333 |
| Personal Allowance (tax-free) | £12,570 | £1,047 |
| Income Tax | −£27,432 | −£2,286 |
| Employee National Insurance | −£4,011 | −£334 |
| Take-home pay | £68,557 | £5,713 |
NI is 2% on all earnings above £50,270.
£100,000 is the most important income threshold in the UK tax system. This is where the Personal Allowance taper begins, and where the effective marginal tax rate jumps to approximately 60% on income between here and £125,140. Every pound earned in this zone costs 60p in combined tax.
The mechanism: For every £2 of adjusted net income above £100,000, HMRC withdraws £1 of Personal Allowance. Since that £1 of allowance was protecting income taxed at 40%, losing it costs an additional 40p in tax — on top of the 40p already paid on the extra £2 income. The total: 60p per £2, or 60%.
The pension solution: Gross pension contributions reduce adjusted net income pound-for-pound. A £5,000 pension contribution when you're at exactly £100,000 ANI prevents the taper from starting at all. The contribution saves you approximately £2,000 in additional tax (restoring £2,500 of PA × 40%) plus the normal 40% relief on the contribution itself.
Act before 5 April: If your salary is exactly £100,000 and you have no other income, you're at the threshold. A bonus, interest payment, or rental receipt that takes you even £1 over starts the taper. Review your ANI position before each tax year end.