China's social security card number is actually the same as the citizen ID number, both of which are 18 digits. The following are the detailed structure and generation rules.： ###1. Composition of ID number (i.e. Social security individual number) **Example number: 11010519900101123X** 1. **Address code (first 6 digits)** -1st-2nd place: Provincial level (11=Beijing) -3rd-4th place: prefecture-level (01= Municipal district) -5th-6th place: county level (05=Chaoyang District) -*For example: 110105 represents Chaoyang District, Beijing* 2. **Date of birth code (7-14 digits)** -Format: YYYYMMDD -*19900101 in the example means born on January 1, 1990* 3. **Sequence code (15-17 digits)** -Bits 15-16: Police station code (range: 00-99) -17th place: gender identification (odd number is male, even number is female) -*123 in the example represents the 123rd male born on the same day in the same area* 4. **Check code (18th digit)** -Calculation steps： -The first 17 digits are multiplied by the weight coefficient: 7,9,10,5,8,4,2,1,6,3,7,9,10,5,8,4,2 -After summing and dividing by 11, use the remainder comparison table to obtain the check code (the remainder 0-10 corresponds to 1,0,X,9,8,7,6,5,4,3,2） - *Example calculation: Assuming that the sum of the first 17 products is 157, 157%11=2, corresponding to X* ###2. Other numbers on the social Security card 1. **Card management number (9-10 digits)** -Example: B123456789 -Structure: Letters + 8 digits (letters represent provinces or banks, and numbers are random sequences) 2. **Financial account number (19 digits)** -Example: 6230510200123456789 -Composition: 6-digit BIN code (bank identification) + 13-digit custom sequence ###3. Special instructions -**Cross-provincial processing**: When applying for a social security card in another place, the address code is still the place of residence and will not be changed. -**Twin case**: If the twins were born in Xicheng District, Beijing on May 5, 2005, the number may be： - Brother: 110102200505051257 (odd sequence code) - Younger brother: 110102200505051268 (the sequence code is even, and the check code is calculated) ###4. Information protection recommendations -Avoid disclosing the full number. If necessary, you can hide the 7th-14th and last three digits, such as:110105****** 123X -It is recommended to set the social security query password to a combination of 8-16 digits with uppercase and lowercase letters and numbers, such as: Zh3ng@2023 These numbering systems ensure the uniqueness of each person's identity across the country, and at the same time reduce the risk of manual input errors through the verification code mechanism. In practical applications, the household registration system of the public security organ will automatically generate an identity card number that meets the rules when the newborn settles in, and the social security system synchronizes this information as a personal identification.