Raw hides and skins that are fresh, salted, dried, or preserved but not tanned fall under headings 4101–4103. Once tanning begins, the material moves to 4104–4106 (wet-blue, crust, or finished leather by species). Further processing such as buffing, embossing, or lacquering after tanning shifts classification to 4107, 4112, or 4113 depending on species. The precise stage of processing at the time of importation determines the correct heading.

Chamois leather, patent leather, patent laminated leather, and metallized leather all fall under heading 4114 regardless of the animal species from which they originate, because the special finishing process is the defining classification criterion rather than the source animal.