Just a sample site of a possible usage of DateTimeExtensions nuget package.
January 01 New Year
March 27 Good Friday
March 29 Easter
March 30 Easter Monday
April 27 Kingsday
May 05 Liberation Day
May 07 Feast of the Ascension
May 17 Pentecost
May 18 Pentecost Monday
December 25 Christmas
December 26 Boxing Day
DateTimeExtensions DateTimeExtensions