20 Groszy

Poland switched its circulation coinage to steel-core planchets in stages beginning around 2013, driven primarily by rising copper and nickel commodity prices making the older solid copper-nickel pieces increasingly expensive to produce. The 20 groszy was among the later denominations converted, with the magnetic plated-steel version entering production for the 2019 dated issues. Vending machine operators and transit systems required recalibration of magnetic sensors across the country following the changeover.