Just a sample site of a possible usage of DateTimeExtensions nuget package.
January 01 New Year
April 09 Good Friday
April 11 Easter
April 12 Easter Monday
April 27 Kingsday
May 05 Liberation Day
May 20 Feast of the Ascension
May 30 Pentecost
May 31 Pentecost Monday
December 25 Christmas
December 26 Boxing Day
DateTimeExtensions DateTimeExtensions