According to "Bidding Law of People's Republic of China (PRC)", the bidder shall provide certification documents that meet the qualifications stipulated by laws, administrative regulations and bidding documents. The bidder's taxpayer qualification can be proved by providing the taxpayer qualification certificate issued by the tax department. In practice, tax authorities usually provide a taxpayer inquiry system. Through this system, bidders can obtain their own taxpayer qualification information and intercept screenshots of the inquiry results as supporting documents. This screenshot can be used as an effective proof of the bidder's taxpayer qualification.