A ZIP+4 code is an extended version of the standard 5-digit ZIP code used by the United States Postal Service (USPS). It is an expanded version of the 5-digit ZIP code that adds an additional 4 digits to the end of the code. These digits are used to further refine mail routing and sorting. This helps the USPS provide accuracy and timeliness of mail delivery.

For example, a New York ZIP code (10001) would be given as 10001-0001 or 10001-0002 if used for different addresses in the same ZIP code. The first 4 digits of the ZIP+4 code indicate either the primary range (10001-0001) or secondary system (10001-0002). The additional 4 digits provide further detail about the exact address.

ZIP+4 codes are used for all types of mail delivery, including bills, advertisements, packages, and private letters. Additionally, many companies, including banks and insurance companies, use ZIP+4 codes for address accuracy when handling customer accounts. This additional information helps ensure that a customer’s information is sent to the correct address and helps to reduce incorrect payments or deliveries.

Using a ZIP+4 code is essential when sending mail or packages, as accuracy and delivery speed can greatly depend on its use. Therefore, it is important to know the complete 9-digit ZIP+4 code for any mail sent out. It is also important to update address information with correct ZIP+4 codes to ensure deliveries are made accurately and quickly.