Not less than 15 years. According to the provisions of the Social Insurance Law, the payment period of basic old-age insurance is not less than fifteen years, and those less than fifteen years can be paid on time. The basic old-age insurance adopts the principle of voluntary payment and overpayment. China Merchants Bank, 1987, established in Shekou, Shenzhen, is the first joint-stock commercial bank wholly owned by an enterprise as a legal person in China and the first pilot bank to promote banking reform from outside the system.