It's a war tax stamp, that's what it says at the top. Might be from Spain or from one of its colonies, they used similar designs.
It's Spanish, from the same set, but only those listed in the catalogues were approved for postal use. Therefore, it's a revenue.
Thank you, Marvin
Scott lists MR 23-26 (5c-20c) as a complete set. I am unable to identify this 30c stamp Comments pertaining to ID & valuation would be appreciated. Thank you, Marvin
re: Spain MR?