NIM31010 | Special Cases: Widows: Ending of reduced liability: Employed widows
From HM Revenue & Customs · National Insurance Manual
Regulation 133 Social Security (Contributions) Regulations 2001 (SI 2001 No. 1004)
An employed widow who stops being entitled to pay reduced rate Class 1 contributions must;
tell her employer immediately, and;
recover her certificate of election from her employer, and;
return her certificate of election to HMRC