First off, I do not understand why the HDHP I had on 12.1.16 has anything to do with my 2017 taxes. Additionally, I do not understand why when I select "self only" it increases my taxes owed by $316. Am I to believe that I'm being punished in the current tax year for having this plan in a previous year? This plan cost me nearly $500 per month in 2016 through my employer and now I have to pay additional taxes on it? I did not even contribute to a HSA in 2017. What gives? Seems like an overreach by our wonderful government.
The 12/1/2016 question has to do with a rule called 'last month's rule'. This rule allows for an individual who was covered by an HDHP on 12/1/2016 to contribute to an HSA as if they were covered for the entire year. If you contribute the maximum to an HSA under this rule, then you must maintain HDHP for the next 12 months (in 2017). Otherwise, excess contribution penalties will apply.
Need more details about your situation. Did your employer contribute to your HSA, did you maintain HDHP coverage throughout the year, did you complete the HSA section completely?