NIC Credits
People who are unable to work for some reason may be able to claim NIC credits (technically credited earnings, since 1987). These are equivalent to Class 1 NICs, though are not paid for. They are granted either to maintain a contributions record while not working, or to those applying for benefits whose contribution record is only slightly short of the requirements for those benefits. In the latter case, they are unavailable to fill "gaps" in past years in contribution records for some benefits.
Read more about this topic: National Insurance