overnight usps cutoff time is the last time a package can be accepted at the USPS post office for overnight delivery via services like USPS Priority Mail Express. The cutoff time can vary depending on the location of the post office, but it is typically in the late afternoon or early evening, around 4:30 PM to 6:00 PM. For the most accurate cutoff time, it is recommended to check with your local post office. USPS Priority Mail Express guarantees overnight delivery, but packages must be dropped off before the cutoff time to ensure they are processed for the next day’s delivery. To avoid missing the cutoff, many customers choose to use USPS online tools to schedule pickups or drop off their packages early.