A top-up state pension designed to supplement the basic state pension. Employees contributed to the additional state pension through payment of class 1 National Insurance contributions (NICs). Originally known as the state earnings-related pension (SERPS), the additional state pension was reformed in 2002 when the state second pension (S2P) was created. Since the new state pension came into effect on 6 April 2016, employees can no longer accrue any further entitlement to the additional state pension, but those who reached their state pension age before 6 April 2016 will continue to receive pension payments for the remainder of their lives.