A benefit crystallisation event (BCE) that is relevant for the purpose of determining the closing value of the pension input amount for a member of a registered pension scheme in respect of a defined benefit or cash balance arrangement. BCE 4 occurs when a member of a money purchase arrangement under a registered pension scheme becomes entitled to a lifetime annuity. The amount crystallised is the purchase price of the annuity. Before 6 April 2024, BCE 4 triggered a test against the lifetime allowance available to a member of a registered pension scheme. Following abolition of the lifetime allowance, BCE 4 remains relevant in the context of the transitional provisions applying to members who used up some or all of their lifetime allowance before 6 April 2024 (Sections 216, 232 and 236 and Schedule 32, Finance Act 2004 and Part 6, Schedule 9, Finance Act 2024.)