USPS Address Correction and Forwarding: What Shippers Need to Know

Bad addresses are expensive. Between customers who move, typos in checkout forms, missing apartment numbers, and addresses that simply don't exist, a meaningful percentage of packages hit delivery problems every day. USPS processes about 6.2 billion address changes and corrections annually, and if you ship any volume at all, some of your packages are caught up in that system. Understanding how address correction and forwarding work helps you reduce returned packages, cut costs, and keep customers from wondering where their stuff went.

How Address Correction Works

When USPS encounters a package it can't deliver as addressed, it checks the Change of Address (COA) database — a massive file of everyone who has filed a forwarding request. If there's a match, USPS either forwards the package to the new address or returns it with corrected information. If there's no COA match and the address is simply wrong, USPS attempts to correct obvious errors (misspelled street names, wrong ZIP codes) and deliver anyway. When that fails, the package comes back to you.

USPS Address Correction Service (ACS) formalizes this process by sending corrected address data back to the shipper. You get the new address, the reason for non-delivery, and the forwarding expiration date if applicable. The cost runs between 10 and 50 cents per correction depending on whether you use the electronic system (OneCode ACS or ACS Fulfillment) or rely on physical endorsements printed on the mailpiece.

Electronic ACS is dramatically faster — you get corrected addresses within 1 to 3 days compared to 5 to 10 days for physical returns. For any shipper doing more than a handful of shipments per week, the electronic option is worth setting up.

Why Packages Become Undeliverable

The most common reason — accounting for about 35 percent of undeliverable-as-addressed mail — is that the customer moved and filed a forwarding request. These packages get forwarded automatically and usually arrive fine, just a day or two later than expected. The second most common reason, at about 20 percent, is a customer who moved without filing forwarding. In that case, the current resident may refuse the package or USPS returns it to you.

Incorrect addresses account for roughly 25 percent of delivery problems. Some of these are fixable — USPS can correct a wrong ZIP code or standardize an abbreviated street name and still deliver the package. Others, like a completely fictitious address, result in a return to sender. Missing apartment or suite numbers cause another 10 percent of issues. The carrier might attempt delivery to the building's central mailroom, but packages often bounce back because there's no way to identify which unit they belong to.

Vacant addresses, refused deliveries, and deceased recipients make up the remaining cases. Each has a different USPS handling protocol, but from the shipper's perspective, the result is the same: an undelivered package that either needs reshipping or a customer service conversation.

Mail Forwarding Rules

When someone files a Change of Address with USPS, their mail gets forwarded for different durations depending on the mail class. First-Class Mail and Priority Mail forward for 18 months — more than enough time for most situations. Periodicals forward for 60 days, and Standard Mail (marketing mail) doesn't forward at all — it gets discarded.

For packages shipped via Ground Advantage or Priority Mail, the 18-month forwarding window means most of your customers' orders will reach them even if they recently moved. After the forwarding period expires, packages are returned to sender. USPS charges a forwarding fee for packages based on the weight and service, typically a few dollars added to the original postage.

One wrinkle worth knowing: forwarded packages take longer to arrive. USPS sends them to the original delivery unit first, which then reroutes them to the new address. This can add 2 to 5 days to the delivery time, and tracking may show confusing scan events as the package bounces between facilities.

Preventing Address Problems Before They Happen

The cheapest way to deal with bad addresses is to catch them before you ship. USPS offers a free Address Validation API that checks addresses against the national database and returns a standardized, deliverable version. Most shipping platforms integrate this automatically — when a customer enters an address, the system validates it in real time and suggests corrections.

Common fixes include standardizing abbreviations ("Street" vs "St"), adding the correct ZIP+4 code, correcting misspelled city names, and flagging addresses that don't exist in the USPS database. Some platforms also flag addresses where the apartment or suite number appears to be missing, prompting the customer to add it before checkout completes.

Address validation catches most problems but not all. It can't tell you that a customer moved last week if they haven't filed forwarding yet. It can't catch addresses that technically exist but belong to a vacant building. And it occasionally marks legitimate new-construction addresses as invalid because USPS hasn't added them to the database yet.

For sellers with a customer database, periodic NCOA (National Change of Address) processing is worth the investment. This service runs your entire address list against the USPS forwarding database and returns updated addresses. It costs a few cents per address and catches moves before they cause delivery failures. Running NCOA processing quarterly keeps your database current and reduces return rates.

What to Do When Packages Come Back

When a package is returned to you, check the endorsement on the label. USPS prints a reason code that tells you exactly why it was returned — moved with no forwarding, address insufficient, refused, vacant, and so on. This information is valuable for deciding your next step.

For customers who moved, attempt to contact them for an updated address before reshipping. For addresses marked insufficient (usually a missing apartment number), reach out for the missing information. For refused deliveries, contact the customer to understand whether they no longer want the product or whether it was a mistake. Only reship after confirming the corrected address to avoid a second failed delivery and double the shipping cost.

Platforms like atoship integrate address validation into the label creation workflow, catching errors before they become returned packages. Combined with automated NCOA processing and clear customer communication about address accuracy, you can push your delivery success rate above 99 percent.