Maria: I doubt that most musical organizations are into double-entry bookkeeping! But if I were to make a guess, it would count as an expense. Admittedly a large one. (a) Sheet music is designed to be used up (per the Fair Use Guidelines). (b) Used sheet music has a value of approximately zero. Ask any insurance agent, but preferably check with a CPA. (c) Many orchestras rent a majority of their music, thereby making it a straightforward expense. Our opinions are meaningless.