In Japan and other Far East countries, a person’s age increments on New Year’s Day, as well as on their actual birthday. It is called as 数え年kazoedoshi.
How to find your kazoedoshi?
Before your birthday, add 2 years. After your birthday, add 1 year.
If your birthday has not come yet the year, you add 2 for your actual age.
If our birthday has already came the year, you add 1 for your actual age.
Once you add your age on your birthday, you won’t add 1 until next New Year’s Day.
In Shinto, most ceremonies related a person’s age use the Eastern Age, therefore Westerners need to add one to their age to get the Eastern Age. Example ceremonies where age is used: Yakuyoke/Yakubarai and the Hitogata used in Toshikoshi-no-Ōharae.
On Setsubun, our Shrine has the custom for people who are having yakudoshi (critical year), request to have gokitō held, such as yakubarai Gokitō ceremony. Request yours at here.