My reading of the Treasury release is that this all has to do with"baselines". Compared to current spending the deal didn't make cuts at all--spending will continue to increase over the next 10 years. The "cuts" are compared to a projection of what would have been spent without the deal, called a baseline. There are various ways of calculating baseline, i.e. how you account for inflation.It seems that S&P's error was related to misunderstanding which baseline the 2.1T applied to.
I understand that it was relative to baseline. But the bottom line we cut 2.1T out of the budget and S&P had advised 4T. This does highlight the issue of how cutting is done, though. The budget had a trajectory of 10T in spending increases over the next decade and now it will be 2.1T less than that. So we will increase our spending by 7.9T and call it a "cut". :)
