here's how i understand it
Refundable tax credits represent a different approach. Since they are a credit, rather than a deduction or exclusion, they do not depend on a
household's marginal tax bracket. A tax credit of $1, for example, reduces taxes by $1 and thus is worth the same to households in the 35 percent
bracket or the 15 percent bracket. And since they are refundable, they provide benefits to all tax filers, regardless of whether they owe income taxes
on net.
Source
If you and your spouse will owe 10,000 for taxes this year - then under this plan, you'll only owe $5000 dollars for taxes, effectively raising your
tax return
my question is:
How is he going to pay for it?
If you have to be in a Health Insurance company already to qualify - then how is everyone going to have access to it?
to further that:
Those obtaining innovative insurance that costs less than the credit can deposit the remainder in expanded Health Savings Accounts.
(From the source in the OP in John McCains policy)
So - you don't get access to that money. It goes into HSA that has even more restrictions on it:
An HSA is intended for those individuals who don't have health insurance or have only major medical coverage. It can also work to the benefit of
some individuals who rarely utilize medical services and are under a group plan that has significant employee costs.
An HSA is like an IRA, but instead of providing retirement benefits, it provides a way to pay for medical expenses on a tax-free basis. Publication
969 states that to be an eligible individual and qualify for an HSA, you must meet the following requirements.
* You have a high-deductible health plan.
* You have no other health coverage (except generally you can have vision and dental).
* You are not enrolled in Medicare.
* You cannot be claimed as a dependent on someone else's 2004 tax return.
source
So if the remainder goes into an HSA
and you are instantly excluded from access to the HSA - because a requirement is:
* You have no other health coverage (except generally you can have vision and dental).
.....im so confused by McCains policy
you're given money that ... you CANT USE
doesnt make sense to me. 
