This might be a dumb question (I’ve only been playing nearly 2 years), but if the key signature is only stated on the first line of the music, would that still apply to the rest of the music or not? I’m going through an audition piece and don’t want to be playing the wrong notes. Thanks.

3 Answers 3


The strict rule is that key signatures are re-stated on every stave. A change from x sharps or flats to zero sharps or flats will be marked with one or more cautionary accidentals at the end of the preceding line. (We used to add 'cancelling naturals' when moving from, say 2 sharps to 3 flats, but modern practice only uses them when moving to NO sharps or flats.)

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But there's the 'Real Book' style that omits key signatures (and even clefs) after the first line. Not too annoying in a simple lead sheet, but problematic when it crept into the orchestra books for Broadway shows, with their frequent key changes!

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(Some people consider this a 'professional' style. They are mistaken.)

I don't think you'll be in any doubt which system is being used after trying the piece both ways - with and without the implied key signature!

  • 2
    If the music has key sig changes it is really annoying if the key sig is not printed on every line. It would be even worse if the music also have clef changes and the clef is not printed on every line. OK, the latter doesn't happen in the real book. Anyway, I agree that lack of key sig on every line has nothing to with "professional" style. So I would say to anyone who writes music: Please always include the key sig on every line. Commented Mar 21, 2021 at 22:46
  • Interesting; do you have a reference describing the "modern practice"? Lilypond still uses canceling naturals as its default. Commented Mar 22, 2021 at 3:25
  • Gould p.93. "CONTEMPORARY PRACTICE At a key change use only the new key signature. This gives a simpler result. A previous key signature requires cancelling with naturals only when the new section has no key signature:" Plus plenty of practical observation.
    – Laurence
    Commented Mar 22, 2021 at 12:59
  • @LaurencePayne: I remember reading in a book (don't remember if it was Gould or something else) that some practices are different for published music or music which would entail multiple rehearsals, versus music which is intended for a one-off performance (such as an advertising jingle). The use of key signatures at the start of every line was considered essential for the former, but not the latter. Does that jibe with what you read?
    – supercat
    Commented Mar 22, 2021 at 17:03
  • @supercat Music of that sort, particularly movie/TV scores, is frequently notated without key signatures at all, with every sharp/flat inlined, to minimize the amount that performers who are essentially sight-reading it have to keep in their heads. Commented Mar 22, 2021 at 19:22

The general standard is to place the key signature at the beginning of every line. However, it's very common in lead sheets to place the key signature only on the first line. In that case, the key signature does apply to the whole piece (unless explicitly changed, of course).


Quite often - usually - when something like this occurs, playing through in both options (there will only be two - with/without key sig.) will give you the answer. One will sound good, the other...

In real/fake books, it's usual to state the key sig. on the first line only, just like you'd find with the time sig., which usually, in all music, doesn't get repeated. Think about it - if the original key sig. needed changing, there'd have to be some naturals cancelling that, in order to be in the new key of C/Am.

So, only if there's a key change will there be another key sig. shown later. Assume the original one carries through the piece.

I've often wondered why the key sig. is repeated for each line, but the time sig. isn't. Another question, maybe...

  • Hah, good point. Let's just say if you pick the wrong key signature, it'll often be quite clear that something's not quite right...
    – user45266
    Commented Mar 21, 2021 at 10:43
  • 3
    @user45266 - unless - you serendipitously think 3b and play in 4#, or vice versa. Been there, done that.
    – Tim
    Commented Mar 21, 2021 at 11:05

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