Like many South East Asian countries, they say that when the baby s born, they are 1 year old. I can't say that I've heard of the Chinese new year thing, but it might well be a local custom in that province/area.
Whatever way they add this extra year, there official age is that of any other country, ....from the day they were born. Bloody confusing at times, MM, had the same sort of problem trying to understand how old Mary was while she was still in the hospital.... I've had the same problems at interviews i've been conducting in China, when they have one age on there resume and another on professional licences...
David....