The tax registration number is 15. The first 3 digits represent province and city area codes, and 4-6 digits represent district and county area codes. 7- 15 digits are consistent with the organization code certificate number, representing the serial numbers of all local organizations. It is your company's only tax code, which has the same function as an ID card. It's your company's ID card.
The numbers used in the industrial and commercial registration number and the tax registration number of an enterprise are not related to each other, and they are different codes of two completely independent systems.