In Taiwan, Christmas is not officially celebrated or legally recognized. However, coincidentally, December 25 is the date of the signing of the Constitution of the Republic of China in 1947, officially the Constitution Day (zh:行憲紀念日).

Hence there was already an official holiday on that date designated in 1963 by the Executive Yuan, which is largely, though unofficially, treated as if it were Christmas.

In order to avoid having too many legal holidays when phasing in two-day-off-per-week plan, the Constitution Day is no longer a full legal holiday with a day off since 2001.

Some people have become disappointed that December 25 has ceased to be a holiday, but there are still unofficial celebrations of Christmas.

Source: Wikipedia