- Provisional postage due usage of 10f stamp with white numerals (Scott # 106)
- Approximate size: 21mm x 25mm.
Due to a shortage of postage due stamps resulting from constantly changing postal rates the Hungarian Post issued an order in June 1915 allowing usage of postage stamps marked with capital letters of `T` or `P` or with the inscription `PORTO`. Many post offices handstamped or marked postage stamps in advance. By mid-November 1918 the use of these provisional postage due stamps was prohibited.