[Vee]

Modern Monetary Theory of a flexible floating fiat currency says that if the government is in surplus than the private sector is in deficit.

There can be no net savings of money by the non-government sector without the government going into deficit.

In more laymen terms, if the government is in surplus, the private sector is losing purchasing power - have less money than they otherwise would (and that can be fine if the economy is going along swimmingly)