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Computerized Delivery Sequence

Computerized Delivery Sequence, or CDS, is a USPS program that gives mailers updated delivery sequence information for the address lists they provide. A mailer qualifies by showing that its list holds at least 90 percent of the possible delivery addresses in a ZIP Code. USPS then sends those addresses in walk sequence, the order a carrier delivers them.

Updated October 31, 202634 sources

What it is

CDS is an updating service that USPS performs on a mailer's own address list. The data comes from the Address Management System, the official USPS record of mailing addresses. Each CDS file is a snapshot of that database, taken every Saturday for weekly customers and on each month's second Saturday for bimonthly ones.

USPS does not sell address lists: a mailer creates its own or buys one from an address list vendor. USPS is bound by Title 39, which keeps it from providing name or address lists to anyone.

The CDS file holds addresses confirmed by Delivery Point Validation, including addresses converted for 911, in walk sequence. It meets all current requirements of the Coding Accuracy Support System and needs no further address hygiene processing. Each update comes with a PS Form 3553, the CASS Summary Report.

CDS gives mailers access to walk sequence saturation discounts. It also reduces undeliverable-as-addressed mail. Mailers can see which addresses are marked vacant or seasonal.

How it works

Eligibility for CDS is decided through Address Sequence Service, a process the Domestic Mail Manual sets out in DMM 507. Electronic Address Sequencing, or EAS, is the electronic way to send a list through it.

A mailer goes from an address list to its first CDS update.

  1. The mailer builds an address list from subscribers, store or website customers, or public county records.
  2. The mailer formats the list in the layout the EAS program requires.
  3. The mailer sends the list with a Delivery Unit Summary and a Processing Acknowledgement Form.
  4. The CDS Department runs Address Sequence Service on the list.
  5. USPS tells the mailer whether the list qualified.
  6. A mailer whose list qualified submits a CDS Application form.
  7. The mailer downloads CDS Conversion Software before its first update arrives.
  8. Updates begin with the next scheduled fulfillment cycle.

Qualifying a list

A mailer can qualify every address in a ZIP Code or only some of its address groups. In each group, the list must hold at least 90 percent, and no more than 110 percent, of the possible deliveries. A possible delivery address is a full, complete address that can receive mail delivery from USPS.

The address groups are:

  • City Res: residential addresses on city carrier routes.
  • City Bus: business addresses on city carrier routes.
  • City All: all addresses on city carrier routes.
  • POB: Post Office Box addresses, residential and business.
  • Rural: rural route and contract delivery service route addresses, residential and business.
  • All: every group, with the list held to 90 percent within each one.

A first-time EAS customer may submit only one ZIP Code. A mailer has three attempts to qualify each ZIP Code or address group in one year from its last submission. Address Sequence Service fees apply whether qualification succeeds or not. That fee is separate from the CDS product fee.

A mailer with a ZIP Code's city residential group may ask to add the city business group if it is under 10 percent of city deliveries. The request goes to the CDS Department in writing.

When USPS creates a new ZIP Code out of an existing one, a mailer may qualify for it automatically. At least 90 percent of the new ZIP Code's addresses must come from ZIP Codes and groups the mailer already receives. New ZIP Codes and major route adjustments usually take effect on July 1 each year.

Bimonthly and weekly updates

The subscription year starts with the February product, which USPS builds in January and sends by the end of January. The other bimonthly products are April, June, August, October and December. Each bimonthly cycle's release date is the 15th of its month. USPS may send a monthly supplemental update when ZIP Codes change significantly. The first update posts to a secure website after the invoice is paid.

Bimonthly data arrives through Electronic Product Fulfillment, or EPF, a secure USPS website for address product files. Since October 2014, USPS has sent all Address Quality and Address Management products through EPF. CDS files stay in the EPF account for up to 60 days from fulfillment.

Weekly CDS, or WCD, delivers CDS updates every week by secure electronic file transfer. Weekly updates come at no additional charge. A weekly customer starts with a Base File of every ZIP Code and address group it qualifies for. USPS issues Base Files in February and August.

Each weekly file holds only the carrier routes that changed. A change can be new addresses, a new delivery sequence, an address moving routes, or new No-Stat or vacancy coding. Weekly files are ready by close of business each Thursday, or Friday when Thursday is a holiday. EPF keeps the current week's file and the three before it. Each company is limited to three users on its account.

A weekly download is one .tar file that holds several ZIP files. Each name inside it has five parts, as in WCD4812_C000010000_F00.ZIP:

PartExampleMeaning
Product typeWCDWeekly CDS; CNG is the Congressional Data File
Date4812Week and year
Customer IDC000010000The CDS customer number
File typeFFulfillment data; D is the document file
File number00File 1; 01 is file 2

The example names the first data file for week 48 of 2012.

Each update includes a PS Form 3553, which documents when the file was processed, as postage discounts require. A Bill of Lading gives the delivery counts for each qualified ZIP Code and address group. Weekly files also carry a Qualified ZIP Code Form.

All CDS files are zipped and encrypted with a password. CDS Conversion Software decrypts them with the password the CDS Department provides. It comes in Windows and UNIX or Linux versions. CDS passwords are lowercase, and WCD passwords are uppercase.

Reading the CDS file

CDS files are in ASCII format. Each record has a record type indicator, a one-byte field that says what kind of record it is.

IndicatorRecord
1Volume Header Record
2ZIP Code Header Record
3ZIP Route Header Record
4Detail Record

Weekly files use different volume and ZIP Code header layouts from CDS files. Their carrier route and delivery point records use the CDS layouts.

Among the delivery point record's fields are these:

FieldWhat it holds
Delivery Sequence NumberThe position of the address on its carrier route
Carrier Route IDA 4-byte route code whose letter is B for PO Box, H contract delivery service, R rural, C city or G general delivery
Address Vacant IndicatorY when the delivery point has been unoccupied for 90 days or more, N when not
Delivery Point Drop IndicatorY for a drop, N for not a drop, C for a Commercial Mail Receiving Agency
Seasonal Delivery IndicatorY for seasonal delivery, E for educational delivery, N for not applicable
Business Family Served CountFor a drop, the number of businesses or families it serves

A drop is a single delivery point that serves several businesses or families. A gated community whose mail goes to a gatehouse is one example.

A hyphen in an address number stands for its first significant leading zero. For example, 0113 MICHIGAN BLVD appears as -113 MICHIGAN BLVD.

The CDS No-Stat file

A CDS No-Stat is a delivery point in the address database that does not receive delivery. Examples include new housing developments and vacant delivery points on rural routes. No-Stat records appear on city, rural and contract delivery service routes, but not in PO Box routes.

The No-Stat file is a supplemental file for current CDS customers, at an additional charge. It uses the CDS file layout and fulfillment schedule. It comes with the relevant eLOT product, at no additional charge, to help merge the records into a list in sequence.

The file lets a mailer begin mailing a new delivery point, or resume mailing a vacant rural route address, when the occupant asks. Its records mark these addresses:

  • K in the Delivery Point Type Code field marks an Internal Drop Address.
  • Y in the CDS No-Stat New Growth Indicator field may mark a new growth address.
  • A, B, C or D in the Delivery Point Code field marks a rural route vacant address.
  • T in the PO Box Throwback field marks a rural route PO Box throwback address.

An Internal Drop Address is a unique address delivered as part of a drop.

Seed addresses

A seed address is a fictitious address that USPS creates and gives to a CDS customer. Seeds help list owners protect address lists they rent or lease. Each seed belongs to one CDS customer.

Address Sequence Service finds the seeds in a submitted list. That keeps another party from qualifying a customer's list without permission. A customer should put seeds in a list only when renting or leasing it.

A customer joins by selecting yes in the Seed Address Options section of the CDS Customer Application/Renewal Form. February and August files carry two seeds for each address group, when available.

Congressional District Code Files

The Address Management System links every address's ZIP+4 code to a congressional district. Mailers match the ZIP+4 codes in their CDS file against the Congressional District Code Files to find each address's district. CDS customers request these files on the CDS Customer Application/Renewal website.

Fees and the subscription

A CDS subscription covers one year of fulfillment, February through January. Fees depend on the number of deliveries in each qualified ZIP Code on the February product build. Each customer pays an annual minimum fee. Each ZIP Code has a minimum fee for its first 1000 addresses and a fee for each address after that.

The CDS FAQs put that minimum at the first 5000 records instead. The CDS Department gives the current fee schedule.

Payment must arrive before fulfillment. USPS takes checks, ACH electronic payments, USPS money orders, and Visa, MasterCard or American Express cards. USPS issues no refunds for subscriptions cancelled during the year.

CDS qualification runs from February 15 through January 15. Customers renew and update their profile at https://cdsrenew.usps.gov.

A customer current on its payments may transfer all or part of its subscription to another party. The transfer needs a Letter of Authorization to Transfer on company letterhead, signed by the primary contact and a company officer. The receiving company must be a CDS customer or apply to become one. Transfer requests must arrive by the first of the month.

A customer cancels ZIP Codes or a whole subscription by written request only. Cancellation requests must arrive by the first of the month.

Rules

The process for qualifying to receive CDS updates specifies that mailers must demonstrate they possess a minimum of 90 percent of the current possible delivery addresses in the ZIP Code™ and/or address group for which they wish to receive CDS updates.

A mailer must show that its list already holds at least 90 percent of the possible delivery addresses in each ZIP Code or address group it wants updates for.

Customers attempting to qualify for CDS must select service level 3 (DMM 507.9.2c), which provides sequencing of addresses, removes undeliverable addresses, and adds missing or new addresses.

A mailer seeking CDS must choose level 3 of address sequencing service, which sequences the list, removes undeliverable addresses and adds missing ones.

Lists may be purchased from others, but you must ensure that you have obtained permission to use the purchased or rented list for the purpose of CDS qualification.

A mailer may buy or rent a list, but must have permission to use that list for CDS qualification.

WCD customers must download all files in date order to maintain the accuracy of their lists.

A Weekly CDS customer must download every weekly file, in date order.

All CDS qualified customers must renew their subscription and update contact information (if applicable) using the CDS Customer Application/Renewal website no later than December 31st each year.

Every CDS customer must renew on the CDS Customer Application/Renewal website by December 31 each year, and update its contacts if they changed.

Payments must be received prior to fulfillment.

A customer must pay before USPS sends the CDS product.

Mailers must ensure this data is used only as intended.

A mailer must use CDS No-Stat data only for the purpose USPS gives it.

The CDS file provides the finest depth of sort available and therefore should not be processed through address matching software.

A mailer should not run a CDS file through address matching software, because the file already has the finest depth of sort.

What goes wrong

  • Failure to renew suspends the CDS product, and the customer must requalify.
  • A customer with an outstanding invoice cannot renew.
  • Failure to pay disqualifies a customer, who must then requalify through EAS.
  • An Address Sequence Service invoice unpaid after 30 days suspends the product.
  • A seed address in a submitted list disqualifies that ZIP Code until the owner or mailer documents proper use.
  • A skipped weekly file leaves routes out of sequence, which could affect postage discounts.
  • For an address with a drop count, mailing both the primary address and the addresses behind it duplicates the mailing.
  • A customer that transfers ZIP Codes loses their CDS data unless it requalifies.
  • A customer that cancels ZIP Codes must requalify to receive them again.

Terms

Address Management SystemAMS, Address Management Service
The national USPS database of every delivery address with its associated ZIP Code, ZIP+4 code, and city/state name that serves as the foundation of data for all address correction tools.
walk sequence
The order in which a carrier delivers mail for a route. This order is required for most carrier route presort mail.
possible delivery
Any stop to which a carrier could make a delivery. A possible delivery could be an active delivery point, a vacant address (designated as such if vacant for more than 90 days and flagged in the address database), or a Post Office Box throwback (designated in the address database as an address that receives free Post Office Box service at a Post Office that has no carrier delivery service or at a Post Office in which the address is within a quarter mile of the Post Office).
Address SequencingAddress Sequence Service
An Address Management Service in which address cards are arranged in order of delivery for city routes, rural routes, highway contract routes, and Post Office Box sections. For a qualifying mailer, address cards with either blank cards added (for missing addresses) or cards containing missing and new addresses may be added. Electronic Address Sequencing service is available for mailers who can electronically submit address files for sequencing.
Electronic Address SequencingEAS, Electronic Address Sequencing Service, Electronic Address Sequence Service
EAS provides an electronic option for processing address files for sequencing and/or qualification for Computerized Delivery Sequence (CDS).
Weekly CDSWCD
WCD provides customers with weekly transaction based CDS product fulfillment through secured electronic file transfer.
Electronic Product FulfillmentEPF, Electronic Product Fulfillment (EPF) web site, Electronic Fulfillment Website
A secure web-based application managed by the National Customer Support Center in Memphis TN that is used to post and receive Address Management and Address Information System products, including ACS fulfillment files.
CDS Conversion Software
CDS Conversion Software allows CDS customers to decrypt their CDS files easily.
Delivery Sequence Number
The number indicating the position of an address on a carrier route.
drop sitedrop
A drop is a single delivery point or receptacle that services multiple businesses/families.
CDS No-Stat
CDS No-Stats are delivery points in the database that currently do not receive delivery.
seed address
Seed addresses are fictitious addresses created by USPS and provided to USPS® CDS customers.

Documents

User Guides

Quick Service Guides

Fact Sheets

FAQs

Data Files

Tools

Contact Lists

Applications/Forms

Contacts

The CDS Department, part of Addressing and Geospatial Technology, answers questions at 1-800-238-3150 or cds.ncsc@usps.gov. Completed CDS application forms go to the CDS Department by mail or by fax to 901-681-4582. Its mailing address is 225 N HUMPHREYS BLVD STE 501, MEMPHIS TN 38188-1001. Questions about EAS go to eas.ncsc@usps.gov.

Sources