Does anyone know:

1. An email address for China Customs Agency
2. How does the China customs calculate your entries from HK?

I understand that you can not enter china on business more than 180 days per year without paying taxes, however I can not find documentation on how they calculate the days.

One of our accountants explained that it is each time you enter (even if 1 min or 24 hours) it will count as 1 day.
Another accountant said that if you go in and return same day, they will count as half day.

Anyone?