What is the non-machinable surcharge for First-Class mail?

The non-machinable surcharge for First-Class mail is $0.21. This surcharge applies to certain pieces of mail that cannot be processed by the Postal Service's automated sorting machines due to their size, shape, or stiffness. For instance, items such as square envelopes, rigid mail, or envelopes with clasps would fall into this category and incur the additional fee. This surcharge is intended to cover the extra handling costs associated with such mail. Understanding this fee is essential for businesses and individuals alike, as it impacts mailing costs and budget considerations.