How to buy three insurances instead of five?

After the implementation of the Social Insurance Law, non-urban household registration personnel will gradually transition from "three insurances" to "five insurances". In order to link up with national laws, at present, they will participate in three social insurances: old-age insurance, medical insurance and work injury insurance. Because some employees have paid the "five insurances" according to the regulations at that time, they can continue to pay the "five insurances" in their original units, but when they leave their original units for re-employment, they must pay the "three insurances" according to the regulations.