Just a sample site of a possible usage of DateTimeExtensions nuget package.
January 01 New Year
April 07 Good Friday
April 09 Easter
April 10 Easter Monday
April 27 Kingsday
May 05 Liberation Day
May 18 Feast of the Ascension
May 28 Pentecost
May 29 Pentecost Monday
December 25 Christmas
December 26 Boxing Day
DateTimeExtensions DateTimeExtensions