NIM30005 | Special Cases: Married Women: Automatic cancelling of election following failure of "2 Year Test"
From HM Revenue & Customs · National Insurance Manual
National Insurance Recording System 2 (NIRS2) cancels a reduced rate election for the following reasons:
LAPSED BY POSTING is where contributions are received two complete tax years or more after the last reduced rate NICs were recorded
LAPSED BY LO 1717 where the cancellation of the election has been manually input
LAPSED FOR RP is where a Retirement Pension calculation is requested and the woman has failed the two year test (see NIM30004)
LAPSED BY CREDITS if credits are posted at least two complete tax years after the last reduced rate contributions