What is the name of Russia's celebration of New Year's Day on January 14?

Russia's celebration of New Year's Day on January 14 is called Old New Year.

Old New Year is observed according to the Julian calendar, which currently falls 13 days behind the Gregorian calendar. In the 20th and 21st centuries, January 1 on the Julian calendar corresponds to January 14 on the Gregorian calendar.

Russia adopted the Gregorian calendar for civil purposes after the 1917 Revolution, but the older date remained present in religious and cultural life. As a result, some people celebrate both the official New Year on January 1 and Old New Year on the night of January 13–14.

Old New Year is generally less prominent than the main New Year holiday. It may involve family gatherings, meals, and parties, but customs vary widely and it is not a separate calendar system used for Russia's civil datekeeping.