The math here is based on the idea that MFA would reduce the per-person expenditures by 19% (19.2% actually)

(1) 5.9% by unilaterally reducing drug prices by 40%
(2) 2.8% by unilaterally reducing medical service prices by 20%
(3) 1.5% through the claim that MFA would have fewer "excess services"
(4) 9.0% from allegedly increased efficiency due to only having to deal with one payer

Is this at all plausible?

Achieving (1) and (2) would be - um - difficult, to say the least! In real life, prices would be set by a political process. Our actual history of attempts to unilaterally reduce medical reimbursement reates is not promising! [see https://en.wikipedia.org/wiki/Medicare_Sustainable_Growth_Ra... or the debate over Medicare drug price negotiation].

(1) & (2) con't: Imposing a single-payer system and then having that payer set prices is effectively the same as imposing a national price control regime, which we in theory could do without MFA. We have not done this, despite the fact that it would save everyone an enormous amount of money. Why not? Because it would be insanely controversial and take a ton of money out of some people's pockets, especially doctors and nurses. Will this be easier under MFA?

(3) The idea that MFA would be structurally less likely to provide "excess" health services seems pretty optimistic indeed. Our military, for example, is not really known for being budget conscious and aggressively efficiency minded. Nor are our state and local level agencies, e.g. the MTA here in NY. Spending policies are set by a political process, and political processes are prone to over- rather than under- spending in every case I can think of.

(4) The 9%(!) savings from "billing efficiencies" is based on an assumption that billing expenses in medical offices will be reduced by 2/3 when there is only a single payer. Why would this be? Billing expenses scale with the number of bills, not the number of vendors. Will MFA lead to fewer procedures on net? Will it eliminate the concept of prior authorizations, which represent the bulk of these "excess" BIR expenses? Will providers and patients not have coverage disputes? Will MFA have dramatically superior automation than private payers? Note that Germany has a multi-payer system and has Canada-like administrative costs [https://www.healthaffairs.org/doi/full/10.1377/hlthaff.2013....]. There are hidden variables here.

Here's the thing:

The most superficial argument in favor of MFA is to look at a country like Canada and say "Canada spends X / pp on healthcare and they have a single payer system, therefore if the US adopts a single payer system, our costs will drop to X!". That's not real analysis, and it ignores all the cost drivers that have nothing to do with the payer. This paper is a drill-down to component costs, but ultimately is no less superficial. MFA billing will be 65% more efficient because Australia billing is 65% more efficient than the US. Prescription drugs will be 40% cheaper because Canada pays 40% less than the US. And so on.

If you could realize any of these cost savings in MFA, you could realize them now. But you probably can't - not easily, anyway, and after burning all your political capital on a $1T/year tax hike it will only be harder. The cost-savings will be compromised to get the medical industry on board, just like it was during the Obamacare debate. And now you can toss this whole analysis in the garbage.

This is wish-casting dressed up in 200 pages of rigorous-looking analysis, designed to get people to read the abstract, then look at the page count, and then treat it as credible.

MFA is not going to save the system money. Take it to the bank.