Military Separation Pay Fairness Act of 2014 - Directs the Secretary of Defense (DOD) to determine whether former members of the Armed Forces who were separated for a violation of the policy concerning homosexuality in the Armed Forces as in effect before the effective date of the Don't Ask, Don't Tell Repeal Act of 2010 were paid: (1) the full amount of separation pay to which they should have been entitled under standard military separation pay laws, or (2) a reduced amount because of homosexuality pursuant to administrative instructions in place at the time of the separation.

Requires the Secretary to pay such a former member who has not received the full military separation pay: (1) the amount of the difference between the full amount and the amount actually paid, and (2) interest on the amount of the difference.

Excludes former members who joined the class-action settlement in Collins v. United States from receiving additional payments for the difference in amounts under such procedures, but provides for former members in such settlement to receive payment for interest on such amount.