Taoist Holy Days or holidays are usually astronomically based.
Taoists typically have a celebration or personal ritual performed on the equinoxes and solstices. These events represent a shift in the flow of environmental yin/yang, being peak times in the solstice and a transition time during the equinoxes. During such times, it is possible to easily build qi, enhance luck or refine karma.
There are many popular Taoist holidays that are also celebrated by ritual sects and not astronomical.
Some Taoist holidays are also Local Religious Holidays. This means that the Taoist in that country, or region have a special holiday that they celebrate that other Taoists do not. Often times these localized events come from the particular sect that is located in that region. Sometimes they exist to celebrate the actions of a famous Taoist within that community.