Presort is a work sharing program offered by the USPS. In exchange for sorting, containerizing, and presenting the mail with appropriate documentation, the USPS offers discounts over the full rate of postage.
It is a common misconception that presorting means placing the mail pieces in ZIP code order. There are different ways to presort the mail based on piece type, class of service, physical characteristics, and barcoding. Grouping these attributes together identify a 'presort method', for which there is a specific set of requirements for sorting and containerizing the mail. Although each method has unique requirements for sorting, many presort methods follow a similar model of sortation. Understanding this model is the beginning of understanding presort.
Mail pieces are sorted into levels. The first level described is the finest level of sortation and provides the biggest discount. The discounts are larger at the finer levels because sortation at those levels provide the largest savings to the USPS in processing the mail. Pieces are grouped according to 5 digit ZIP codes. The pieces are placed into trays to the same 5 digit destination. All full trays to a destination are created, then overflow trays are sometimes allowed (which are not full to capacity).
Any pieces that could not be used to fill trays at the 5 digit level then fall down to the 3 digit level. At this level, pieces are collected into groups to the same 3 digit ZIP codes. Thus, combining 5 digit ZIP codes together can fill trays to the same 3 digit ZIP codes that otherwise could not have been filled at the 5 digit level. Sometimes overflow trays are allowed.
ADC Level Any pieces that could not be used to fill trays at the 3 digit level then fall down to the ADC level. ADC stands for 'Area Distribution Center', and is a distribution hub within the USPS distribution system. At this level, pieces are collected into groups served by the same ADC. Combining 5 digit ZIP codes together can fill trays to the same ADC that otherwise could not have been filled at the 3 digit level. Sometimes overflow trays are allowed.
Mixed Level All remaining pieces are consumed at the mixed level. Pieces are grouped together into trays until no more pieces remain. Trays are not required to be filled at this level although full trays must be created if possible.
The 5 digit trays benefit the USPS the most as they can be shipped directly to the destination post office serving the 5 digit ZIP code of the tray without any further processing by the USPS. Each subsequent level can be moved through the USPS distribution a shorter distance to its final destination before processing is required by the USPS. Therefore, as you progress through the levels, a smaller discount is provided to the mailer.
When the trays of mail are delivered to the post office, they must be accompanied with Qualification reports and bundle reports that detail how the mail was sorted. Additionally, postage statements must be presented that identify the number of pieces being presented at each rate, and the total amount of postage including any postage due.
There are numerous other restrictions on discounted mailings. First Class mail requires a minimum of 500 pieces while a Standard Class mailing requires a minimum of 200 pieces or 50 lbs of mail. A permit is also required to produce presorted mailings for which there is an annual fee. Mail lists must be processed with CASS certified postal coding software and have been processed by an approved move update solution.
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