The last day to ship UPS for Christmas is usually on December 23rd. However, please keep in mind that this is only a general estimate and the specific date may vary depending on your location and shipping method. It's always best to check with UPS directly for the most accurate and up-to-date information. Additionally, it's important to note that shipping times may be longer than usual due to the busy holiday season. To ensure your package arrives in time for Christmas, it's best to plan ahead and ship as early as possible.