NIM70750 | Class 2 National Insurance contributions: general information: higher rate provisions
From HM Revenue & Customs · National Insurance Manual
Section 12 of the Social Security Contributions and Benefits Act (SSCBA) 1992
The late payment higher rate provisions (HRP) will continue to apply in the following circumstances:
to all Class 2 NICs paid in respect of periods prior to 6 April 2015
from 6 April 2015, to Class 2 NICs paid voluntarily by self-employed earners who have profits below the small profits threshold
to self-employed earners who pay Class 2 NICs outside Self Assessment
For more information on HRP see NIM72150