You were never allowed to contribute $7100 plus more. Even if you had family coverage all year, that is both your personal limit and your overall family limit.
HSA eligibility is determined on the first day of the month. Your spouse is considered to be covered by a family HSA, even if you are the one who owns the plan, as long as she does not have disqualifying coverage.
Therefore, you and your spouse's individual eligibility for 2020 should be
August 0
Sept $591.66
Oct $591.66
Nov $591.66
Dec $295.83.
That $591 family limit applies to both spouses combined so your overall eligibility for 2020 should be $2366.64, with a maximum allowed to either spouse of $2070.81.
My math doesn't match yours, I would need to see your worksheets, which I can't do. I suspect you reported you had coverage for August, you did not because it counts from the first of the month, but that by itself doesn't make your numbers match mine. Did you have an HDHP at any time before August 4?
However, you can also use the last month rule. I don't know why Turbotax is not picking this up. Is there a question you missed? Under the last month rule, you are deemed to have had the same coverage for the entire year as you had on December 1, provided that you maintain that same coverage for all of the next year (2021). So if you use the last month rule, you and your spouse could each contribute $3550 for 2020, because you each had separate self-only HDHPs on December 1, 2020.
That still gives you an over contribution of $3550 to your account, which you must withdraw before April 15 to avoid a penalty. This is not a normal withdrawal, it is a return of excess contributions, which may require a special form from the bank. The money will be added back to your taxable income.
However, you could deposit up to $2200 into your wife's account and take a tax deduction. You can make a deposit that is designated for 2020, up until April 15, 2021, as long as you tell the bank in advance (there should be a selection on the web site if you do it online.)
I don't get where you see $4011, but these are the numbers as I calculate them.
@dmertz
