In May 2016, HHS released final regulations on healthcare discrimination, including transgender issues.
Trade press here
https://transequality.org/blog/hhs-issues-regulations-banning-trans-health-care-discrimination
Detailed FAQ here
http://www.transequality.org/sites/default/files/HHS-1557-FAQ.pdf
Actual 2016 final regulation here
https://www.federalregister.gov/documents/2016/05/18/2016-11458/nondiscrimination-in-health-programs-and-activities
81 FR 31376 (May 18, 2016; effective July 18, 2016)
This rulemaking was undertaken to implement ACA Section 1557; more here and here. This section of the ACA is written in very brief and dry legalese and merely refers to nondiscrimination (in the ACA) on the grounds of other laws including the Civil Rights Act of 1964, etc.
RELATIVE TO ACA 2018: SCALING BACK PER JUDGE
In April 2018, HHS announced plans to scale back the impact of this regulation, certainly in the context of transgender persons, based on a prior Court Order specific to this regulation. In stating so, HHS/DOJ were responding to a court order and a judge in Texas. The NYT doesn't name the court case but attributes it to "eight states, a network of Roman Catholic hospitals, and the Christian Medical & Dental Association." The CMDA has 19,000 members.
https://www.nytimes.com/2018/04/21/us/politics/trump-transgender-health-care.html
Somewhat ironically, a separate judicial ruling appears to uphold a Texas state law regarding discrimination as it applies to transgender issues (Wittmer v Phillips).
https://www.jdsupra.com/legalnews/title-vii-in-transition-texas-federal-35938/
Note that while the scale-back was announced in response to a judicial order, the Administration would have various options in handling the order - compliance, appeal to a higher court, etc. Both left and right administrations have the option to rapidly comply with an order they find palatable and fight several years against an order they object to.
RELATIVE TO MEDICARE HOSPITAL POLICY 2016
In July 2016, CMS proposed standalone hospital rulemaking that combined two topics: (a) discrimination in Medicare, including transgender issues; and separately, (b) hospital antibiotic stewardship programs.
http://www.discoveriesinhealthpolicy.com/2018/04/brief-blog-communicating-and.html
https://www.federalregister.gov/documents/2016/06/16/2016-13925/medicare-and-medicaid-programs-hospital-and-critical-access-hospital-cah-changes-to-promote
Yes, it's a little confusing, because at about the same time HHS released final regulations on transgender and discrimination under ACA Section 1557 (May 2016), and CMS released somewhat similar proposed regulations specific directly to the Medicare program (July 2016). This July 2016 proposed CMS regulation hasn't been finalized but CMS has 36 months to do so (July 2016 to July 2019), under SSA 1871.
RELATIVE TO PRISONS
There is also 2018 policymaking regarding transgender status in prisons.
https://www.dallasnews.com/news/texas-politics/2018/01/04/trump-likely-undo-obama-era-transgender-prisoners-policy-ending-texas-court-battle
RELATIVE TO CMS NCD ON MEDICARE & TRANSGENDER SURGERY
CMS reversed a decades old ban on transgender surgery Medicare coverage in 2014.
http://www.discoveriesinhealthpolicy.com/2014/05/judges-reject-decades-old-medicare-ban.html
CMS formally described transgender surgery as a condition and therapy for local coverage decisions in 2016.
http://www.discoveriesinhealthpolicy.com/2016/06/cms-posts-draft-decision-on-gender.html
RELATIVE TO "CONSCIENCE CLAUSE" REGULATION
Separately from the administration and court case on the implementation of ACA 1557 discussed above, a "conscience regulation" at HHS is under comment in early 2018.
https://www.hrc.org/blog/hrc-responds-to-the-trump-pence-admin-launch-of-unnecessary-conscience-divi