If a HDHP medical plan covers domestic partners, are domestic partners eligible to open an HSA?

The same eligibility rules apply to a domestic partner as anyone else related to opening an HSA. If the domestic partner meets the HSA eligibility requirements, he or she would be eligible to open an HSA. Furthermore, since domestic partners are not considered spouses by the IRS, domestic partners are considered to be two unattached individuals, and each would have their own HSA contribution limit if they both have HSAs. However, domestic partners can't use their HSA to pay for their partner's health expenses, unless they claim their partner as a federal tax dependent. Individuals should seek tax guidance from a tax attorney related to tax dependency of domestic partners. Individuals who can be claimed as dependents on another person's tax return are not eligible to open their own HSA. Note: The IRS has ruled that same-sex couples who were legally married in a jurisdiction that recognizes same-sex marriages will be treated as married for all federal tax purposes, even if the couple lives in a jurisdiction that does not recognize the validity of same-sex marriages. For federal tax purposes, the terms "spouse", "husband and wife", "husband" and "wife" include an individual married to a person of the same sex if the individuals are lawfully married under state law, but that such terms do not include individuals who have entered into a registered domestic partnership, civil union, or similar formal relationship recognized under state law that is not denominated as a marriage under that state law.