500.000 Rials

Iran's rial had depreciated so severely by the early 2020s that a 500,000-rial note — once unthinkable — became a practical necessity for everyday transactions. The currency had lost roughly 60% of its value between 2018 and 2021 alone, driven by compounding sanctions and domestic inflation running well above 40% annually. Issuing high-denomination notes was the Central Bank's operational response to a cash economy that had simply outrun its existing note range.

P#164A sits at the top of the rial series as currently catalogued. The colour-shifting ink is a relatively recent security upgrade for Iranian issues, reflecting pressure to deter increasingly sophisticated counterfeiting of high-value denominations.