For every £2 of additional net income above £100,000 and up to £123,700, the PA will decrease by £1. Therefore the taxable income will increase by £3 The additional £3 of taxable income will then be taxed at 40% = £1.20 So £1.20 tax is effectively charged for every £2 of actual additional income in this band – £1.20 on £2 = an effective 60% rate