The postal service of the country of origin identifies and marks shortpaid mail with a T stamp. Next to the T is a fraction that consists of the amount of postage deficiency (expressed in its own currency) divided by the country’s international surface letter rate at the first increment.
The receiving exchange office in the United States multiplies the T fraction by the U.S. First–Class Mail International letter rate to determine the short paid amount in U.S. currency. This amount, plus a $0.50 handling charge, accounts for the postage-due amount to be collected on delivery. The postage-due formula is as follows:
