Music Business/Law Tips - "Arrangements"

If you are arranging an old song already in the public domain, then you can copyright your new arrangement/version of the public domain work [see copyright.gov for form]; however, with respect to royalties from exploitation, when you register the new work with ASCAP or BMI since its a contemporary arrangement of a public domain work, they have some sort of committee that applies a formula comparing the original version to your new version to see if the new version has changed significantly (i.e., amount of new material) and will give you a writer percentage based on their review (e.g., they might agree to give you 50% writer credit/income instead of 100% as if it were a brand new song you wrote); record companies will normally pay mechanical royalties based on whatever bmi/ascap has determined is your percentage.

If your arrangement is of a contemporary song that is not yet in the public domain, under the copyright law only original words and music are copyrightable and in general an arrangement is not considered copyrightable (except in the rare case of public domain arrangements that are significant - see above); so under this scenario you would not be able to claim copyright (unless you contacted the original publisher and they agree to make you a co-writer of the derivative works which is rare or everyone would be trying to say they cowrote song with the Beatles, etc), but you can list yourself as arranger for what its worth since that is true.