1609
Bank of Amsterdam
The Wisselbank takes mixed coin and credits a bank guilder merchants can transfer.

In 1609 Amsterdam opened a public deposit bank. Mixed street coin went in. A standard bank guilder came out, transferable on the city’s books. That bank money often traded at a premium, the agio, over worn coin.
The reputation was that a bank florin was a claim on metal. Concealed lending later broke that reputation. 1609 is the opening, not the later breach.