Ahem... "Suppose your bank announced a negative 3...

Ahem... "Suppose your bank announced a negative 3 percent interest rate on your bank deposit of 100 dollars today. Suppose also that the central bank announced that cash-dollars would now become a separate currency that would depreciate against e-dollars by 3 percent per year. The conversion rate of cash-dollars into e-dollars would hence change from 1 to 0.97 over the year. After a year, there would be 97 e-dollars left in your bank account. If you instead took out 100 cash-dollars today and kept it safe at home for a year, exchanging it into e-money after that year would also yield 97 e-dollars."
https://blogs.imf.org/2019/02/05/cashing-in-how-to-make-negative-interest-rates-work/