The Commercial Overprint Society of Great Britain (COSGB) is an online association of people who share an interest in commercial overprints.

Commercial overprints (or as they are sometimes called, security overprints) are postage or revenue stamps that have been commercially printed with the name of the user prior to being used.

In Great Britain, Ireland, and New Zealand, these stamps were used to pay an excise tax and were applied to receipts of various sorts. They were generally not supposed to be used for postage, but there are exceptions to this rule. The first overprint user, the Oxford Union Society, used overprints exclusively for postage. And after the end of the excise tax in 1971, firms used their remaining overprints as postage. Other countries used commercial overprints differently: in Canada, New South Wales, and Victoria, these overprints appear only on revenue stamps; in Ceylon, Hong Kong, and Japan they appear only on postage stamps and were used only for postage.

COSGB focuses primarily on the commercial overprints of Great Britain. We are in the process of creating printable checklists of British commercial overprints, in addition to the online catalogue we are developing.

Our other main initiative is an online newsletter that presents topics in the field of commercial overprints. Your comments and criticisms are welcome—you can even submit an article, if you like.

COSGB is unusual in that membership is free, our publications are free, and our preferred method of communication is electronic. If you are interested, we will contact you by email when each new edition of the newsletter is released; just click on the Join COSGB button for details. Alternatively, you can just return here and click the Newsletter button on the left side of this page at your convenience.

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