OneCode ACS

OneCode ACS allows customers mailing First-Class Mail, USPS Marketing Mail, or Periodicals (flats or letters) to receive electronic or automated address corrections through the use of the IMb. Technical information regarding the Intelligent Mail barcode is available at — scroll down to the section titled “Featured Resources.”

Information embedded in the IMb includes the Mailer ID, which is used to identify the mail owner or mail service provider. The Sequence Number can be used to identify the customer, or it can be used to identify the mailpiece itself. The Service Type Identifier in the IMb represents the ancillary service requested, and on First-Class Mail it can replace the printed endorsement. USPS Marketing Mail still requires a printed endorsement.

Use of the IMb allows for a less “cluttered” address block (as illustrated below in Exhibit 1) on the mailpiece, and when used on letters may provide automated notices and lower address correction fees.

Exhibit 1: OneCode ACS Mailpiece

sample of a onecode ACS mailpiece

  1. The Intelligent Mail barcode applied to the mail contains the following information:
    1. Presort information (flats only).
    2. Service Type Identifier that requests specific services like ACS and/or Informed Visibility (IV).
    3. Mailer ID that identifies the mail owner or mail service provider.
    4. Serial or sequence number that uniquely identifies the mailpiece or the addressee.
    5. Routing information that provides the ZIP Code and delivery point validation that allows the mail to be sorted directly to the address.

Note: The optional printed “Ancillary Service Endorsement” (not shown) provides the Postal Service with the sender’s instructions on how to handle the mail if it is UAA. When using the IMb on First-Class Mail letters, the printed endorsement is optional. On USPS Marketing Mail, the printed endorsement is still required.

Technical information on OneCode ACS is available at — scroll down to the section titled “ACS Technical Guides.”