20 Euros

The European Central Bank was established in June 1998, and the euro banknote series was not issued for circulation until January 2002 — meaning any note dated 1998 reflects the institutional founding year printed on the statute of the ECB, not an actual issue date. The notes of the first series carry a 2002 release regardless of what appears in the catalog record. A 1998-dated 20 euro in paper form almost certainly refers to a specimen, a pre-production proof, or a catalog misattribution worth investigating before pricing.