Do USPS Shipping Labels Expire? | Shipping School Technically, USPS shipping labels expire 28 days after you purchase them. Maybe "expire" isn't the right word; 28 days is the cutoff point when USPS deems the labels no longer valid. All this said, USPS generally gives a 2-3 day grace period for shipping labels. However, each Post Office operates differently based on their own discretion.