I sometimes see a natural where it is unnecessary. Sometimes it is a courtesy natural but other times the note has not been flattened or sharpened at all and yet I see a natural that is already there because of the key signature.

Sometimes I see a flat on a note that is already flat. The most common note I see this on is Bb. Like there might not be any B naturals and yet I see a flat on a Bb. This could cause quite a bit of confusion. Some people might think it must be Bbb or A whereas some might think that it is still Bb.

A similar thing is true for a sharp on a note that is already sharp. Some people might think it must be Fx or G whereas some might think that it is still F#.

So why do people put naturals where they are completely unnecessary, flats on already flat notes, and sharps on already sharp notes?

  • I’m voting to close this question because it's vague and over-broad. There are many reasons for courtesy accidentals that depend on context — as shown by the variety of answers here. This topic would be better served by a specific example asking what that particular courtesy accidental is included.
    – Aaron
    Dec 25, 2023 at 8:43

4 Answers 4


They are still courtesy accidentals. They are there because the editor/composer feels like the performer would benefit from it being there it. It could be any reason from it's the first time this note is encountered in this piece so they want you to know the quality of it or it's due to the arrangement being slightly different and they want to be very explicit with what you play.

To the second part of your question, if you know how to read music it's not confusing and is very straightforward. The accidentals override the key signature and anything that comes before them so just from that it is crystal clear what you play.

  • 3
    About half of the annotations I make to music I'm preparing is courtesy accidentals on top of what the editor considered necessary (the rest is fingerings and footings). Nov 1, 2015 at 5:53

A different voice or or instrument or octave might have had a note with a different accidental previously. That's not sufficient when the accidental is actually needed in this voice/instrument/octave but it renders the situation confusing enough that its absence is also indicated explicitly.

The situation is similar with a clef change: if a local accidental is to be either continued or discontinued after a clef change, either requires a new accidental, just for the sake of avoiding confusion.

  • But what I am talking about with the flat on a note that is already flat is where there hasn't been any naturals or sharps and yet I see the flat there. And as I said some people might think that this is a double flat whereas others might think that is is the same flat they have been playing all along. Same thing for the sharp on a note that is already sharp, that is no change at all and yet there is a sharp there. Again some people might think that this is a double sharp whereas others might think that it is the same sharp that they have played previously.
    – Caters
    Oct 31, 2015 at 20:09
  • 1
    No. I've never seen a double accidental being denoted as a redundant one, while redundant accidentals out of courtesy are quite common .Also bear in mind that in a lot of music accidentals tend to depend on context, e.g. a note may have an accidental in an ascending sequence and lose it in a descending one,of vice versa. Nov 1, 2015 at 22:51

It's also possible that this happens due to the music notation SOFTWARE. As is noted by the OP, there isn't a particular good reason to have a "rogue" accidental out there in the bars, unless it's a courtesy.


Another, not yet mentioned reason for seemingly superfluous accidentials might be a change in notation convention. During the renaissance and baroque (roughly until 1750), the general (though not strict) rule was that an accidental is cancelled by a note of a different pitch or a rest. This makes,e.g, the following notation for an embellished syncope dissonance necessary (abc notation with L:1/4, i.e. 1 means quarter note, 2 means half note, / means eight note, etc., and ^ means a sharp)):

e2 a6 ^g1 ^f1 ^g2 a8 ||

which would read in modern notation

e1 a2- | a ^g/^f/ g2 | a4 ||

For renaissance music, it is quite obvious that the modern rule of cancellation at a bar line could not apply because there were no bar lines. Barless music in the baroque was a rare exception (most notably the prélude non measuré) , but the notation tradition with respect to accidentals carried on.

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