Just a sample site of a possible usage of DateTimeExtensions nuget package.
January 01 New Year
April 04 Good Friday
April 06 Easter
April 07 Easter Monday
April 27 Kingsday
May 05 Liberation Day
May 15 Feast of the Ascension
May 25 Pentecost
May 26 Pentecost Monday
December 25 Christmas
December 26 Boxing Day
DateTimeExtensions DateTimeExtensions