(a) Individuals: Hong Kong Identity Card (HKID) number. The Hong Kong Identity Card (HKID) is an official identity document issued by the Immigration. HKID Card numbers are commonly collected and used by an organisation1 to identify individuals and manage records related to them. To align with international practices, the IRD uses Hong Kong Identity (HKID) numbers and business registration numbers for that purposes. A123456(3) is valid because the sum is divisible by 11.