Checking the Accuracy of Your Address List

Why bother?

First, to claim commercial USPS Marketing Mail and First-Class Mail prices, you MUST have checked the accuracy of ZIP Codes within the timeframes listed below. When you fill out and sign your postage statement you are certifying your mailing qualifies for the prices claimed.

Second, look at these statistics:
  • 17% of Americans change addresses annually.
  • 45 million people move each year.
  • Approximately one out of every six families moves each year.

How many of these people are your customers or members?

Just because you buy or rent a list does not mean that the addresses are correct, checked, updated, or "certified." To make sure that you are getting a list with accurate addresses, ask about the National Deliverability Index (NDI) of the list. The NDI rates the percentage of addresses in a list that are deliverable. Use the NDI to target the address elements you need to get the delivery -- and postage price -- you want. For example, if you are targeting a specific 5-digit ZIP Code, look for an NDI of 100% for address element.

To qualify for You must verify By this Date
Presorted 5-digit ZIP Code Within 12 months of mailing
Automation Complete addresses Within 95 days of mailing
Carrier Route Carrier route information Within 90 days of mailing

The Postal Service offers many ways to check the accuracy of your list. Vendors also offer USPS-approved products and services for address list maintenance.

Your local Post Office or Business Mail Entry Unit can help you choose the best option for cleaning up your mailing list. Here are some of choices:
  • Use to check the ZIP Codes in your list.
  • Process your address list through CASS-certified software.
  • Address List Correction Service. You can submit a printout of your list to the Postal Service and we will mark any changes. There is a fee for this service. It is available through your Address Management System Office.
  • NCOALink. A licensed vendor will run your mailing list through special software that updates addresses for your customers who have filed a change-of-address with the Post Office. The advantage to using NCOALink is that you clean up your list BEFORE you mail. You also know in advance how much it's going to cost you (because a vendor charges by the address). With an ancillary service endorsement you get the same result (a corrected address) AFTER you mail, and you don't know how much you'll pay in fees until AFTER the corrections come back.
  • Address Information System (AIS) Viewer. An interactive application designed to provide the ability to retrieve, view, and print accurate and current ZIP Code information for all 50 states on demand, eliminating hardcopy reports.
  • Move Update is required for all mailings at commercial First-Class Mail and USPS Marketing Mail prices. A USPS-approved method must be used within 95 days of the date of mailing. NCOALink includes Move Update. Using NCOALink satisfies the Move Update requirement.
  • What does "CASS-certified" mean? "CASS" stands for "Coding Accuracy Support System." It means that your addresses have been checked for accuracy against the Postal Service's database using an approved system.

Phone: National Customer Support Center (NCSC) at (800) 238-3150.