usps overnight cutoff time is the latest time you can drop off a package for USPS to guarantee next-day delivery via their Priority Mail Express service. The cutoff time varies by location and can range from late afternoon to early evening. It’s important to check with your local post office to determine their exact cutoff time for overnight services. USPS also offers guaranteed delivery by a specific time, such as by noon or 3 p.m. the next business day. Be sure to check with the post office if you’re planning to send an urgent item to meet the deadline.