The State Earnings Related Pension Scheme (SERPS), originally known as the State Earnings Related Pension Supplement, was a UK Government pension arrangement, to which employees and employers contributed between 6 April 1978 and 5 April 2002, when it was replaced by the State Second Pension. The purpose of the scheme was to provide a pension in relation to your earnings, in addition to the basic State Pension.
Employees who paid full Class 1 National Insurance (NI) contribution between 1978 and 2002 earned a SERPS pension. Members of occupational pension schemes could be 'contracted out' of SERPS by their employer, in which case they and the employer would pay reduced NI contributions, and they would earn virtually no SERPS pension.
The principle was that everyone would receive a SERPS pension of 25% of their earnings above a 'lower earning limit' (approximating to the amount of the basic State Pension). The scheme was phased in over twenty years so that those retiring before 1998 received a SERPS pension proportional to the number of years that they had made contributions to it. There was an 'upper earning limit' of about seven times the lower earning limit, beyond which earnings were disregarded for NI contributions and calculation of SERPS pensions.