Tax Identification Number (TIN)
Hong Kong Inland Revenue Department (the IRD) does not issue TIN for communication with the taxpayer. To align with international practices, the IRD uses Hong Kong Identity (HKID) numbers and business registration numbers for that purposes.
Individuals: Hong Kong Identity Card (HKID) number, issued by the Immigration Department under the Registration of Persons Ordinance (Cap 177).
Companies or entities: Business Registration (BR) number, issued by the Inland Revenue Department under the Business Registration Ordinance (Cap 310)
See the source of above information from OECD website : [Read-HK]
TIN - China
See the information for TIN in China: [Read-China]