District of Columbia has explicit insurance guidance on transgender-related health care.

Statutes:

• DC Official Code § 31-2233.11, Unfair Discrimination (2022)
  Summary:

  “No person shall refuse to insure, refuse to continue to insure, or limit the amount of coverage available to an individual because of marital status, race, color, personal appearance, sexual orientation, gender identity or expression, matriculation, political affiliation, or an individual’s status as a victim of an intrafamily offense, sexual assault, dating violence, or stalking."

Bulletins and Announcements:

• Bulletin: Revised Bulletin 13-IB-01-30/15 Prohibition of Discrimination in Health Insurance Based on Gender Identity or Expression
  Issued by: Commissioner McPherson
  Issued on: Feb. 27, 2014
  Summary:

  “In determining the medical necessity of services and benefits provided to such patients, insurance companies should refer to the recognized professional standard of medical care for transgender individuals requiring treatment for gender dysphoria, which is enumerated in the most recent edition of the World Professional Association for Transgender Health Standards of Care (“WPATH Standards”).”

• Bulletin: Bulletin 13-IB-01-30/15 Prohibition of Discrimination in Health Insurance Based on Gender Identity or Expression (2013)
  Issued by: District of Columbia Department of Insurance, Securities and Banking
  Issued on: March 15, 2013
  Summary:

  Exclusions for services related to sex reassignment violate DC's prohibition on discrimination based on gender identity or expression and are no longer enforceable.