Is there such a document for the standard of project budget reduction?

Generally, when bidding, there is a budget price (calculated according to the figure and quota), and in addition, the bidding control price (generally 7% ~ 10%) should be set, which is the upper limit of the downward float. If your bid price is higher than the control price, it is a waste bid, and the lower limit of the fluctuation range is more complicated. First of all, you should make sure that there is a certain profit according to your cost (no profit is malicious competition), and analyze the description of how much the downside is lower than the cost price in the bidding documents, and formulate an appropriate downside rate. Generally, the person in charge (boss) sets the price, and the person who prepares the budget makes analysis and provides reference opinions. The principle is to increase the possibility of winning the bid, and not to waste it.