II. ELIGIBILITY
A. The work must be created specifically for the eligible feature-length motion picture.
B. The work must be the result of a creative interaction between the filmmaker(s) and the composer(s) and/or songwriter(s) who have been engaged to work directly on the motion picture.
C. The work must be recorded for use in the motion picture prior to any other usage, including public performance or exploitation through any media whatsoever.
D. Only the principal composer(s) or songwriter(s) responsible for the conception and execution of the work as a whole shall be eligible for an award. Expressly excluded from eligibility are all of the following:
1. music supervisors
2. partial contributors (i.e., any writer not responsible for the overall design of the work)
3. contributors working on speculation
4. producers and/or arrangers not responsible for the creation of the original song or score
E. A score shall not be eligible if:
1. it has been diluted by the use of pre-existing music, or
2. it has been diminished in impact by the predominant use of songs or any music not composed specifically for the film by the submitting composer, or
3. it has been assembled from the music of more than one composer.
F. No more than one statuette will normally be given in the Original Score category. A second statuette may be awarded when two credited composers function as equal collaborators, each contributing fully to the original dramatic underscore for the film. In cases where three or more credited composers function as equal collaborators, a single statuette may be awarded to the group. Each composer must agree to the single “group statuette” option by signing and returning a Group Award form prior to the submission deadline. Final determination of the awardable composers in the group will be made by the Music Branch Executive Committee.
G. No more than two statuettes will normally be given in the Original Song category. A third statuette may be awarded when there are three essentially equal writers of a song. The Music Branch Executive Committee has the right, in what it alone determines to be a very rare and extraordinary circumstance, to award a fourth statuette. In cases where an established musical group has authored a song, a single statuette may be awarded under the group name in place of individual statuettes for each songwriter. Each of the credited songwriters must agree to the single “group statuette” option by signing and returning a Group Award form prior to the submission deadline. Requests for a group statuette are subject to final approval by the Music Branch Executive Committee.
H. In the case of an original musical, the composer or adapter of the instrumental score may qualify for an award if his or her contribution is deemed relevant and substantial.
I. The Music Branch Executive Committee shall resolve all rules interpretations and all questions of eligibility.
J. It is within the sole and confidential discretion of the Board of Governors to determine what awards, if any, shall be given.
Fuente:
http://www.oscars.org/oscars/rules-eligibility