[Xorakios]

The economic definition of "legal tender" is sometimes obscured in casual conversation.

It isn't "issued by a sovereign state" - that's "fiat" but rather "used for paying taxes." And sometimes, like in the US, debts ("all debts foreign and domestic").

Certainly it has to vary among countries of which I am ignorant, but generally in the Anglosphere it is debts, not payments, that trigger the definition of "legal tender."