The amount due for each unit for which payment is required to be made is based on the prevailing rate for a 1-ounce Share Mail letter or postcard (the Unit Price). Current prices appear in Notice 123, Price List, which is available at http://pe.usps.com/text/dmm300/Notice123.htm. The account holder must pay the Postal Service the prevailing Share Mail price for each static or unique IMb letter or postcard at the time the mailpiece is scanned (as opposed to distributed).
The account holder must distinguish between 1-ounce letters and postcards by the use of separate MIDs. The Postal Service may sample the address side of mailpieces to ensure that the account holder is using the correct MIDs. The account holder is liable for the prevailing postage price based on the mailpiece size regardless of which MID is used.
