Arrangers, especially in a cappella music, are always looking for songs to arrange. And once they make an arrangement, especially a good one, those arrangers are often asked for copies. What should they do?
Some give away the arrangements, some sell the arrangements. But, unless the arranger has permission from a composer, selling or gifting copies of arrangements is illegal.
Thankfully, there is an exception: The Public Domain.
Works in the Public Domain are free for anyone to use in any way they choose. You won't need to make any payments, and you won't need anyone's permission. The trick is knowing whether a particular published song is actually in the Public Domain or not.
The chart below can go a long way towards helping you determine the answer. All you need to know to begin, is when the work was first published. Once you have that, you're off!