an expiration date, which encouraged spending and discouraged money from sitting in a saving account. In the end, 90% of vouchers were spent in shops. Demurrage could be implemented, such as by shaving off fractions of the value on a scheduled basis, as a supplement to traditional inflation targets. Financial safety: CBDC would provide an alternative to fractional reserve banking for daily uses, for those who want to avoid all risk of bank runs, despite the relative safety provided by deposit insurance. Risks Despite having potential advantages, CBDCs remain a controversial topic, and there are risks associated with their implementation. Banking system disintermediation: With the ability to provide digital currency directly to its citizens, one concern is that depositors would shift out of the banking system. Indeed, in the last century, commercial banks have created money thanks to deposits in addition to a number of other ways. Formally they have used 2 methods: fractional reserve banking and zero reserve. Zero reserve: Today, commercial banks in some countries (US, UK, EU, etc) don't need a reserve requirement anymore. Indeed, every time a subject (a person, a corporation, etc) asks for a loan, and that subject offers a loan guarantee (a private property like a car, a building, etc), the bank temporarily creates a new deposit (money), lends this money to them, and when the borrower pays off the loan plus the interest the initial deposit is deleted, and the bank keeps the interest. In the real world, zero reserve and fractional reserve are the same, because the banks are able to avoid the reserve requirements. CBDCs are fully reserved, so if a person wants this form of money, they just buy it from the central bank. In this case commercial banks don't create debt or new money, and they don't earn any interest. Customers may deem the safety, liquidity, solvibility, and publicity of CBDCs to be more attractive, weakening the balance sheet position of commercial banks. In the extreme, this could precipitate potential bank runs and thus make banks' funding positions weaker. However, the Bank of England found that if the introduction of CBDC follows a set of core principles, the risk of a system-wide run from bank deposits to CBDC is addressed. A central bank could also limit the demand of CBDCs by setting a ceiling on the amount of holdings. Centralization: Since most central bank digital currencies are centralized,