Serbia Postage Due Stamp, Numeral in Oval Frame

Serbia · 1911 · 5 para

This is a postage due stamp from the Kingdom of Serbia. The design features the numeral '5' prominently in the center, indicating the amount due, enclosed within an ornate oval frame. The Cyrillic inscription "ПОРТО МАРКА" (Porto Marka) translates to 'Postage Due Stamp'.

Issued in 1911, these stamps were used to collect unpaid or underpaid postage from the recipient of a letter. This series was in use during a period of significant political tension in the Balkans, just a few years before the outbreak of World War I.