Just a sample site of a possible usage of DateTimeExtensions nuget package.
January 01 New Year
March 25 Good Friday
March 27 Easter
March 28 Easter Monday
April 27 Kingsday
May 05 Liberation Day
May 15 Pentecost
May 16 Pentecost Monday
December 25 Christmas
December 26 Boxing Day
DateTimeExtensions DateTimeExtensions