For example China already is experimenting with digital "money" you can only spend until specific date (before it expires) so people won't have savings (needles

For example China already is experimenting with digital "money" you can only spend until specific date (before it expires) so people won't have savings (needless to say they also control who pays for what and can even block you completely once you say something the state doesn't like). Israel is not a cashless society yet but already requires people to specifically declare cash savings exceeding certain (pretty humble) amounts even if they have already declared the income and paid the taxes.