Private overprint

However, while in Great Britain privately overprinted stamps usually served as receipts for tax payments, in 1859, upon application of the Oxford Union Society, there was a unique instance of a private overprint being approved for application on the face of stamps.

Private overprints can also originate from speculative philatelic purposes produced deliberately with a view to selling them to unsuspecting collectors.

For instance, German sympathisers in the Sudetenland privately overprinted Czechoslovakian stamps with swastikas before the annexation, and in Italy, after the fall of Mussolini and his establishment of the Italian Social Republic, stamps of the King were overprinted with fasces by Fascist sympathizers.

[citation needed] There have been several American examples of postal cards being overprinted with a private overprint revaluation shortly after a rate change, including the Post Office Department's authorization of a special Pitney-Bowes Tickometer surcharge to be used to revalue postal cards in the possession of General Electric when the postcard rate went up to 3 cents in August 1958.

The USPS also authorised overprinting of the 10¢ Tractor Trailer and 5¢ Canoe Transportation coil stamps.