Can the company find out whether you are married or unmarried?

Legal analysis: Yes, when paying social security.

Legal basis: Provisional Regulations on the Collection and Payment of Social Insurance Premium Article 16 Social insurance agencies shall establish payment records, including basic old-age insurance and basic medical insurance, and record them in personal accounts according to regulations. Social insurance institutions are responsible for keeping payment records and ensuring their integrity and security. The social insurance agency shall send a personal account notice of basic old-age insurance and basic medical insurance to the payer at least once a year. Payment units and individuals have the right to inquire about payment records in accordance with regulations.