As explained in NIM25001, a person is not entitled to pay (ie, is precluded from paying) Class 3 NICs in certain circumstances. One of those is that a married woman or widow cannot pay for any tax year during the whole of which a reduced rate election is in force (see NIM30000 for married women; NIM31000 for widows).
Mrs K was born in 1956. In March 1976, she elected, as a married woman, that from 6th April 1976:
In May 2003, concerned about her future pension entitlement, she
chooses to revoke that election with effect from 1st June 2003 (
NIM30011).
Mrs K is precluded from paying Class 3 NICs for the 1975/76
to 2002/03 tax years. During the whole of each of those years, she
had a reduced rate election. If she needs to, though, and so long
as she is not precluded from doing so for some other reason, she
may pay Class 3 NICs for the 2003/04 tax year. The election was not
in force for the whole of that year as she revoked it from 1st June
2003.
For details of the other circumstances in which a person is
precluded from paying Class 3 NICs, see
NIM25006 - NIM25015 and
NIM25017.