Before 1 February 1920, two currencies were used in Poland. After the occupying powers left Poland (Germany in the northern area and Austria in the southern area), Fenigs and Marks were used in former German occupied Poland and Hellers and Crowns in former Austrian occupied Poland. On 1 February 1920, the currencies and the administration of Poland were unified and Fenigs (Fenigów) and Marks (Marek) were used in Poland, named after Pfennigs and Marks in Germany.
In 1920, two series of general duty revenue stamps were issued in the unified Fennigs and Marks currency.
An imperforate series and a perforate series (perforation 14½) with blue stamps for the Fennigs and brown stamps for the Marks, depicting the Polish eagle as the national emblem of Poland.
Fenigów and Marek are Polish currency derived from the German Pfennig and Mark.
Marka is a Polish feminine noun. Polish numerals from 2 to 4 are declined as plural: 2, 3 and 4 Marki. All numbers from 5 onwards are treated as quantities: 5, 6, etc. Marek.
Opłata stemplowa = Stamp duty.