Is it legal to ask the project manager to pay social security for three months when bidding?

It is illegal to ask the project manager to provide social security for three months when bidding. According to public information, Article 18 of the Bidding Law of People's Republic of China (PRC) can require potential bidders to provide relevant qualification documents and performance in the bidding announcement or invitation letter according to the requirements of the bidding project itself, and conduct qualification examination for potential bidders; Where the state has provisions on the qualifications of bidders, such provisions shall prevail. The tenderer shall not restrict or exclude potential bidders with unreasonable conditions, and shall not discriminate against potential bidders. Article 20 The tender documents shall not require or indicate specific producers and suppliers, and shall not contain other contents that tend to or exclude potential bidders.