Dates Aren’t Everything
The date stamped on your carton of milk doesn't necessarily mean you should toss it on that date. Because the dating system is not required by the government except on baby formula and baby food, the expiration dates on milk and other food containers serve simply as handy guidelines.
It Could be Past Its Prime
Even though drinking or cooking with milk that has passed its expiration date most likely won't hurt you, use common sense about it. Smell it before using it; if the scent is "off," throw it out.
Milk generally stays fresh for up to five days after the date on the carton, but it's better to be safe than sorry. Note the date on the milk before you buy it, purchase the carton stamped with the latest date available and then use the date as a guideline, not a rule. Your nose is likely the best judge.