The Scott Catalogue of Errors on U.S. Postage Stamps is the definitive reference for major production errors on United States postage stamps. Extensively reviewed and updated for its 20th edition, this volume brings together authoritative listings, research, and values for one of the most specialized areas of U.S. philately.

Released in February 2026, the 20th edition represents a major update to the Errors catalog. Hundreds of values were reviewed and updated, new full-color illustrations were added, and additional listings appear for the first time as ongoing research continues to expand the documented record of U.S. stamp errors.

All listings are identified by Scott numbers and classified by major error type, including imperforates, color-omitted errors, and inverted designs. Each entry is presented within the established Scott catalog framework relied upon by collectors, dealers, and researchers.

The Errors catalog also includes information found nowhere else in the Scott catalog system, such as known quantities, production details, and cautionary notes. Values are provided not only for major errors, but also for error-like imperforates and printer’s waste.

For context and reference, the catalog includes a detailed overview of freaks and oddities, helping collectors distinguish true major errors from other unusual production varieties. Sections Included

The Scott Catalogue of Errors on U.S. Postage Stamps contains the following major sections:

Imperforate error stamps

Error-like imperforates

Color-omitted errors

Hologram-omitted errors

Back-inscription errors

Invert errors

Printer’s waste

Freaks, oddities, and other unusual stamps

Softcover, pages.