Social Security and Medicare Parity Act of 2015

Amends title II (Old Age, Survivors and Disability Insurance) (OASDI) of the Social Security Act with respect to the determination of a valid marriage to account for marriages in jurisdictions other than a state.

Authorizes the courts of any state to find that an OASDI benefit applicant and an insured individual were validly married in a jurisdiction other than a state at the time the applicant files a benefit application or, if the insured individual is dead, at the time the individual died.

Waives the nine-month marriage requirement to make eligible for widow or widower benefits certain widows or widowers whose marriage to a deceased individual would not have been treated as a marriage for federal law purposes before June 26, 2013. Waives the same requirement for anyone who became a stepchild of the deceased individual as a result of such a marriage.

Waives the one-year marriage requirement to make eligible for husband's or wife's OASDI benefits certain husbands and wives whose marriage to an individual would not have been treated as a marriage for federal law purposes before June 26, 2013. Waives the same requirement for anyone who became a stepchild of the individual as a result of such a marriage.

Directs the Commissioner of Social Security to conduct a comprehensive and effective three-year outreach campaign to encourage benefit applications by individuals newly eligible for OASDI benefits as a result of changes in law relating to same-sex marriage and occurring on or after June 26, 2013.