The last day to send Christmas packages varies depending on the shipping method you choose. If you want to ensure that your package arrives before Christmas, you should send it at least 10 to 14 days before December 25th. For international packages, you may need to send it even earlier. If you're sending a package via the United States Postal Service (USPS), the last day for domestic packages is December 16th. For international packages, the last day is December 8th. If you're sending a package via FedEx or UPS, the last day for domestic packages is December 20th.