What Will Happen If You Get the ZIP Code Wrong?

In addition to the residential or commercial address, every package shipped within the United States (or to the United States from abroad) requires a ZIP Code to get to its destination without delays. But what will happen if you get the ZIP Code wrong while the rest of the address is correct? Will your package be returned to you, lost, or simply delayed? Let’s figure it out together.

A ZIP Code is a type of postal code used by the United States Postal Service (USPS). Postal codes by most national postal services to facilitate mail processing and delivery; they are assigned to geographical areas and sometimes also to individual addresses or institutions that receive large volumes of mail. A mailpiece is usually transported to the post office indicated by the postal code in the address, and then delivered to the recipient or stored in the post office for pickup.

The USPS has been using the ZIP Code system since 1963; the acronym ZIP stands for Zone Improvement Plan. A standard ZIP Code is a five-digit code where the first digit represents a group of states, the next two digits represent a region or large city in that group of states, and the final two digits represent an area of the destination city, village, or town. The first three digits are collectively known as the ZIP code prefix; they designate a sectional center facility that serves a certain geographical area.

The United States Postal Service regards the ZIP Code as the primary identifier of a package’s destination. Packages where the ZIP Code matches the rest of the address are delivered quickly and efficiently because they are processed automatically by mail sorting equipment and do not require manual handling. However, when the ZIP Code does not match the city or state in the address, it is difficult for the USPS to determine the actual destination of the package. This is actually very common: according to the USPS, almost a quarter of all mailpieces have something wrong with the address.

Packages with an incorrect ZIP Code are initially processed automatically and dispatched to the post office indicated by that incorrect ZIP Code. If a package cannot be delivered there, the postal workers will review the it, try to identify the destination post office by the city and state in the address, correct the ZIP Code, and forward the package to the right destination post office. If postal workers are unable to identify the correct post office, your package will probably be returned to sender as undeliverable.

So, if all information in the address (street name and number, city, state) is correct save for the ZIP Code, the package will most likely still get delivered to the intended recipient, but it will be delayed because of manual handling and the time it takes to transport the package from the “wrong” post office to the right one. The time of delay will depend on the distance between the two post offices, the one indicated by the ZIP Code and the presumed intended destination post office.

While the USPS will do its best to deliver your package even if it has a wrong ZIP Code, we recommend that you double-check the address before mailing the package. The good news is that most services for printing shipping labels online have an integrated ZIP Code validation tool, so you will get a notification if the ZIP Code does not match the rest of the address. If you don’t know the correct ZIP Code, you can reach out to the recipient or look it up online.

And what if you notice that the ZIP code is incorrect after purchasing and printing a shipping label but before mailing the package? Can you just cross it out and write the correct one instead? The answer is no, because information about your package is already in the USPS system and encoded in the shipping barcode that is scanned during automated processing. To correct the mistake, you need to cancel your shipping label and generate a new one with the correct ZIP Code.