Refrigerated, ready-to-eat, TCS food must be discarded within seven days. The date a product is opened or prepared counts as day one and it can be kept for an additional six days. For example, food prepared or opened on April 1 must be used by April 7 or discarded.
Making a food with multiple ingredients will require using the date of the oldest ingredient. For example, burgers cooked and cooled on June 1 are then used to make chili on June 3; the final use by date will still be June 7, based on the burger cooked date.
There are some exemptions to the seven-day requirement, see the Regulations for more details.