Just a sample site of a possible usage of DateTimeExtensions nuget package.
January 01 New Year
March 21 Good Friday
March 23 Easter
March 24 Easter Monday
April 27 Kingsday
May 01 Feast of the Ascension
May 05 Liberation Day
May 11 Pentecost
May 12 Pentecost Monday
December 25 Christmas
December 26 Boxing Day
DateTimeExtensions DateTimeExtensions