The idea to issue #cbdc dates back decades ago, but it is only since quite recently that some central banks are seriously considering this possibility. What are the reasons, what are the designs, and why now? Come with me...1/x
First, note that the vast majority of central bank money is already digital - the sight deposits of commercial banks have at the central bank. But households and nonfinancial firms cannot access this money directly, only indirectly via the commercial banks. 2/x
Instead, physical cash is a direct claim on the central bank, and once its is in circulation, it can be exchanged directly without the need for intermediaries. 3/x
But cash use has been declining for years - see the pic for the case of the uk- , thus opening up the question of whether we need a digital complement: a digital direct claim in the central bank that can be exchanged without middlemen 4/x 
Now the covid19 crisis and the (not fully warranted) concerns that banknotes and couns may transmit the virus has accelerated this development. See: bis.org/publ/bisbull03…
For central banks, declining use of cash poses two problems. First, a core mandate of central banks is to guarantee that the payment always works - imagine the damage done to the economy payments dont work. 5/x
Second, central banks need to provide a payment means accessible to everyone, including the unbanked. 6/x
So this is the case for issuing a Retail #cbdc: to make for a payment means that is accesible to all and that is not subject to insolvency or technical risks of intermediaries. 7/x
And how can this be achieved? Its a formidable design challenge and there are important design tradeoffs. Technical design considerations can be found here:
bis.org/publ/qtrpdf/r_…
bis.org/publ/qtrpdf/r_…
And here are some design approaches: bis.org/publ/qtrpdf/r_…
