In philately, an omnibus issue is an issue of stamps by several countries with a common subject and which may share a uniform design. Omnibus issues have often been made by countries under common political control or groups of colonies due to the close co-operation required to produce the issue. Omnibus issues are to be distinguished from joint issues which are usually much narrower in scope.

The first omnibus issue

The first omnibus has been said to be the issue of 1898 by the Portuguese colonial empire to commemorate the quatercentenary of Vasco de Gama's discovery of the sea route to India.

British Empire and British Overseas Territories issues

Omnibuses have been particularly associated with stamps from the former British Empire, now the British Commonwealth, due to the large number of territories participating. Initially designs were identical for each colony with only the values, colours and colony names varying. Over time, however, a wider range of designs has been used within the same issue. The first issue was the Silver Jubilee issue of 1935. Many others have followed, usually on themes related to the British Royal Family, but also for subjects such as Freedom from Hunger (1963) and the 1966 Football World Cup. Not every colony necessarily participates in every issue, although the revenue produced by the stamps is a valuable source of income for many smaller colonies/countries which may have few other ways of raising funds. A list of British Omnibus issues is given below: 1935 - Silver Jubilee 1937 - Coronation 1966 - Royal Visit to the Caribbean 1972 - Royal Silver Wedding 1973 - Royal Wedding Princess Anne 1974 - Churchill Centenary 1977 - Royal Silver Jubilee 1978 - 25th Anniversary of Queen Elizabeth's Coronation 1980 - Queen Mothers 80th Birthday 1981 - Charles and Diana Royal Wedding 1982 - Princess Diana 21st and other Birthdays 1985 - Life and Times of Elizabeth the Queen Mother 1990 - Queen Mother's 90th Birthday 1997 - Queen Elizabeth Golden Wedding

French omnibus issues

1931 - Colonial Exposition 1950 - Tropical Medicine 1952 - Military Medals 1954 - Liberation Anniversary

Other omnibus issuers

The omnibus remains popular with countries whose philatelic marketing is handled by the Inter-Governmental Philatelic Corporation as it enables those countries to market their stamps into the lucrative United States and European thematic stamp market by featuring subjects popular in those countries. These issues have, however, been criticised for not being relevant to the culture of the participating countries, for instance stamps featuring Disney characters issued by poor African countries.

Commercialisation

While most earlier omnibus issues were genuine attempts to help a group of countries celebrate an anniversary or event, the fact that these became popular with stamp collectors tempted issuing authorities to bring out more stamps than would have otherwise been thought necessary. These were often heavily marketed.