Just a sample site of a possible usage of DateTimeExtensions nuget package.
January 01 New Year
March 29 Good Friday
March 31 Easter
April 01 Easter Monday
April 27 Kingsday
May 05 Liberation Day
May 09 Feast of the Ascension
May 19 Pentecost
May 20 Pentecost Monday
December 25 Christmas
December 26 Boxing Day
DateTimeExtensions DateTimeExtensions