Contracted out/in
From ACT Wiki
Pensions - UK.
The terms 'contracted out' and 'contracted in' were applied to UK Occupational pension schemes in relation to the State Second Pension (S2P).
A UK pension scheme was 'contracted out' where it provided benefits in place of S2P and 'contracted in' where it provided benefits in addition.
With effect from 2016, contracting in/out ended with the introduction of the UK State Pension.