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National Change of Address (NCOA) Service
How NCOA works
NCOA service is offered by licensees of the USPS. The source of the NCOA data is a permanent Change of Address (COA) filed by a relocating postal customer. Approximately 40 million COAs are filed annually. The NCOA database is updated weekly with this information and changes are kept on file for four years. Data from permanent COA cards from the entire country is transmitted to the USPS National Customer Support Center. (Temporary moves are not carried on the NCOA database.) The data is compiled, edit checks are performed, and transaction tapes are relayed weekly to licensees, which operate under a non-exclusive license of the USPS. Your list is standardized, ZIP+4 is added and then compared with the data on the NCOA file. Address change information is provided to you when your customer's name and address information matches the name and address information on the NCOA database.

Each record contains the relocating postal customer's name along with an old and new address. The old address is compared to the NCOA customer's list for matching purposes and the new address is returned, if a match is made, to the customer. The typical profile of the new address information contained on the NCOA file is as follows:
  • 84 percent are forwardable moves (contain address information)
  • 13 percent are moved, left no forwarding address
  • 3 percent are PO Box closed
  • Less than 1 percent are foreign moves.
Change of address information is controlled by strict name and address matching logic. To make the best use of the information returned from the NCOA process, it is best to understand the NCOA matching logic. All matches made to the NCOA file require an exact match on address. The required name matching is determined by the move type on the NCOA file. The NCOA file is composed of approximately 47 percent family moves, 47 percent individual moves, and 6 percent business moves.
Move Types and Name Matching Requirements are as follows:
  • Individual Move: A match on first name, middle name/initial, surname and title is required.
  • Family Move: Also referred to as a household move. This requires a match on surname only.
  • Business Move: This requires a match on business/firm name.
When possible, postal customers who move multiple times within the three-year period are linked, or chained, to ensure that the latest address is furnished when an NCOA match is attained. This is not always possible if subsequent COAs are not filed in exactly the same manner as the COA filed previously (e.g., if move types are different - such as family and individual - they will not be chained).

Limitations of NCOA
NCOA is a good service, but it is not a complete mail list cleanup system. You can receive address changes through NCOA that are not available in other ways, and there are changes you will not receive from NCOA. Whether or not you receive new address information from NCOA depends on several things: the relocating postal customer must have filed a change of address, the information itself that is provided by the relocating postal customer and the ability of their local post office to tap into an automated address system. Also, the demographic and geographic makeup of your list and the quality of the data in your list will affect the results of the NCOA processing. You may want to use other methods to find the address changes that NCOA doesn't provide.
Input file requirements to avoid pre-list processing fees:
  • Fixed length records and fixed length fields
  • Comma quote or tab or tab quote delimited files with field identifiers and maximum field lengths
  • dBase III compatible files
  • No memo fields and field names beginning in numerics
  • No duplicate field names within dBase file
  • Data must be standard ASCII or EBCDIC text with no packed fields and no null characters
  • File must be in the "copy" or transfer mode, not in the "backup" or save/restore mode except as noted above.
One file per order:
Multiple files must be of the exact same format and/or layout. Also, output is available that requires little or no processing on your part after NCOA (Output format C). Contact Publishing and Distribution for more information about special processing options and associated fees.

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