The PS Form 3600-EZ, Postage Statement - First-Class Mail - Easy - Nonautomation Letters, Cards, or Flats is a form you need to use when sending letters, postcards, or flats that meet the standards of First-Class Mail non-automation prices. It belongs to the "easy" (EZ) forms that may be paid by pre-cancelled stamps, permit imprint, or meter.
The document was issued by the United States Postal Service (USPS). The latest version of the statement - also known as the USPS Form 3600-EZ - was released on January 1, 2018. A printable PS Form 3600-EZ version can be downloaded below or found on the USPS Forms website.