Overprint - Private Overprints

Private Overprints

Any overprint that does not originate from a stamp-issuing authority is considered a private overprint or private cancellation. Such overprints almost always invalidate a stamp for postal use. Most countries treat unofficial overprints the same way the United States Post Office does: the USPS Domestic Mail Manual states that stamps "overprinted with an unauthorized design, message or other marking" are not valid for postage.

Private overprints generally remain outside the formal realm of philately, although individual issues can achieve notoriety through their popularity or aesthetic appeal. Private overprints are typically political messages or commercial promotion.

Stamps owned by commercial entities have sometimes privately overprinted the backs of their purchased stamps. These overprints are usually made as control marks or accounting information. Such overprinting does not invalidate a stamp unless it shows through the front.

• A German 1926 private commercial overprint.