U.K. Class 2 contributions penalty

[Killer007ie]

I have made contribution payments ( Class 2 ) from 2006 up until the years 2018-2019. I am wondering what is the penalty for late payment of future top-up contributions . In other words, if going forward I paid for the present year plus a back payment for 1 more year, what is the penalty amount?

 

[Mayo1969]

AFAIK you can pay up to 5 years back without any penalty