Postage can be paid by stamps, meters and permit imprint. Some smaller agencies with little mail volume use stamps for all their mailing needs. They can also print the amount on labels which can be attached to the envelopes. As envelopes are metered, the postage balance on the meter is reduced by the corresponding amount. Agency staff can periodically take each meter to the post office, or for a fee post office staff will come to the agency and charge the meter on site.
Some agencies use permit-imprint mail for special mailings.
This type of postage can be used for mailings in which all pieces are the same size and weight. Agencies deposit funds in an account with the USPS, and the account is charged for the amount of postage incurred on a specific mailing. Due to its limitations, this method of paying postage is not appropriate for all mail. When it can be used, however, agencies save the staff time required to meter envelopes prior to mailing. All of these variables lead to confusion and inefficiency at many agencies.