This is a particularly clear and succinct explanation of the role of Treasury auctions in monetary operations at Pragmatic Capitalism (hat tip BondSquawk), in a post I urge you to read in its entirety, “The Myth of the Great Bond “Bubble.”
The government bond market is merely a monetary tool that the central bank utilizes to control the cost (or supply) of money by controlling the level of reserves in the system. So, when the government auctions bonds they are merely targeting reserves in the system. This action is mandated by Congress as an accounting tool and so is seen as a source of funding, however, in reality the Central Bank is merely draining reserves that the Treasury already spent into existence – reserves that were deposited at various banks (read this process in greater detail here). Therefore, it’s incorrect to argue that there won’t be buyers of U.S. bonds – with the banks earning 0.25% on their reserves and the government offering anything above that (depending on duration) the trade is a no-brainer for the banks who hold these reserves. The government is basically offering them free money and the Central Bank keeps control of the money supply in exchange (at least in theory). What is not occurring is some sort of funding mechanism. The Fed could care less if the auctions are 2X, 3X or 4X oversubscribed. They don’t get extra money when this occurs. They don’t get a gold coin that can then be spent. So long as they meet the 1:1 bid to cover the auction is a huge success because they drained their targeted reserves and convinced Congress that we aren’t going bankrupt.
Yves here. This is the part most people don’t appreciate: the Federal government spent PRIOR to the bond auction by crediting bank accounts. The government does not fund its spending via bond auctions.