Between 6 April 2020 and 5 April 2023, tapering applied if you had both a threshold income over £200,000 and an adjusted income over £240,000. The tapering worked by reducing your AA by £1 for every £2 of your adjusted income over £240,000 (subject to a minimum AA of £4,000 for adjusted incomes of £312,000 or more).
Prior to 6 April 2020, tapering applied if you had both a threshold income over £110,000 and an adjusted income over £150,000. The tapering worked by reducing your AA by £1 for every £2 of your adjusted income over £150,000 (subject to a minimum AA of £10,000 for adjusted incomes of £210,000 or more).