Once your income passes £100,000, your tax-free allowance starts to shrink. Between £100,000 and £125,140, the effective tax rate climbs to 60%, but smart planning can help.

If you earn over £100,000 in any tax year your personal allowance is gradually reduced by £1 for every £2 of adjusted net income over £100,000 irrespective of age. This means that any taxable receipt that takes your income over £100,000 will result in a reduction in personal tax allowances.

Your personal Income Tax allowance would therefore be reduced to zero if your adjusted net income is £125,140 or above. Your adjusted net income is your total taxable income before any personal allowances, less certain tax reliefs such as trading losses and certain charitable donations and pension contributions.

If your adjusted net income is likely to fall between £100,000 and £125,140 your £12,570 tax-free personal allowance is gradually tapered. This tapering continues until your allowance is fully withdrawn at an income level of £125,140. This effectively results in a 60% marginal tax rate on income between £100,000 and £125,140.

For example, if your adjusted net income is £110,000, you would lose £5,000 of your personal allowance. This additional £5,000 is taxed at 60% due to the combined effect of the 40% higher rate of Income Tax and the partial loss of the personal allowance.

If your income sits within this band you should consider what financial planning opportunities are available in order to avoid this personal allowance trap by trying to reduce your income below to £100,000. This can include giving gifts to charity, increasing pension contributions and participating in certain investment schemes.