Just a sample site of a possible usage of DateTimeExtensions nuget package.
January 01 New Year
April 17 Good Friday
April 19 Easter
April 20 Easter Monday
April 27 Kingsday
May 05 Liberation Day
May 28 Feast of the Ascension
June 07 Pentecost
June 08 Pentecost Monday
December 25 Christmas
December 26 Boxing Day
DateTimeExtensions DateTimeExtensions