I am writing a bassline for a song in Em and there is a passing note A# or Bb in the approach notes. How do I write this note? Since the key signature has one sharp, is it best to write the accidental as A#?

  • 3
    Seeing that bassline would be advantageous. (Along with what else is happening in the surrounding bars).
    – Tim
    Jun 13, 2019 at 8:28
  • 2
    The title asks about accidentals in general, but the actual question is about a passing note. Is the question general, and the passing not just an example?
    – user9480
    Jun 14, 2019 at 13:19
  • Writing music down is purely pragmatical business: the sole purpose is to make a musician produce the correct sounding music when seeing the paper music later. If your notation achieves this, it's good. If it does so with maximum ease for the musician, it's excellent. So write it down, and look at it day-after-tomorrow, when you have forgotten what you tried to write. If you can read it correctly and without any confusion at the first glance, you got it right. If theory says otherwise (as it sometimes does, especially when double accidentals come into play), feel free to improve on the theory.
    – Bass
    Jun 15, 2019 at 11:31
  • 1
    Hang on, I actually meant this one: When is a note flat/sharp? Jun 15, 2019 at 18:46

5 Answers 5


If it really IS a passing note, 'sharpen it going up, flatten it going down' is a good guideline. This has nothing to do with the key signature.

A and B below involve a different set of decisions than C and D.

enter image description here

  • 3
    Also notice that, e.g. in sample B, if you started with an A#, you'd have to follow with an A[naturalsign] . That's clumsy. And the same in reverse for sample A. Jun 13, 2019 at 14:53
  • 3
    Which is part of the thinking behind 'sharps up, flats down'. Jun 13, 2019 at 17:26
  • I didn't vote Laurence Payne's example down, but it's amusing that he breaks his own "rule" penultimate bar by writing E flat not D sharp. Not to mention the fact that D sharp is a better spelling for the augmented 6th chord than to spell it wrong, and name it wrong in the chord symbols, as a dominant 7th. In fact the final three chords sound like an imperfect cadence in A minor with a couple of chromatically altered chords, and are not in E minor at all. But apart from all that, it's a perfect answer :)
    – guest
    Jun 13, 2019 at 23:10
  • @guest -- that F7 is a tritone substitution for B7, leading to Em
    – user39614
    Jun 13, 2019 at 23:48
  • @guest - the point isn't whether we choose to label the F7 'classically' or as a b5 substitution, but whether it's appropriate to think linearly or harmonically. Jun 14, 2019 at 8:18

It really depends on your harmonic structure. It depends firstly on the scale you are in and then what you are trying to do.

When you have sharps in the key signature, you'll most likely use sharps as accidentals.

You'll choose your accidental depending on where you want to move afterwards. The case usually is sharp when you move up, flat when you move down. So, if you are in E minor (F# in the key signature) and you want to have a chromatic movement from A to B, you'll have A -> A# -> B; similarly if you want to move chromatically from B down to A, you'll have B -> Bb -> A.

  • 2
    Beginning of the 3rd para.: aren't accidentals those notes which are outside the key? Those # and b that are in the key sig. can't be accidentals, can they? They are on purpose!
    – Tim
    Jun 13, 2019 at 8:08
  • @Tim haha, no idea why I wrote it that way Jun 13, 2019 at 8:08
  • This answer seems to be missing the point that it's a passing note, not a structural one. Jun 13, 2019 at 11:46
  • @LaurencePayne how is the answer missing the point? Your answer is the same with examples Jun 13, 2019 at 17:50
  • True. I guess it's that I addressed the actual question first then mentioned another one. You did the wrong one first! But I haven't downvoted anyone. Jun 13, 2019 at 20:29

Adding to Shev's answer, it also ought to reflect the harmonic structure of what chord is being represented. Although this is often ignored to make things easier to read. E.g. going from C>F, using C+ as the harmony, the G♯/A♭ should be the former, as the G has been sharpened; If going from F>C through Fm, the G♯/A♭ ought to be A♭, as that reflects the m3 of Fm.

Often in diminished chords, the fourth note of the chord is 'wrongly' spelled. E.g. in Co, it's actually B♭♭, but gets written as A. Technically wrong - but far easier to read, so is oft used. For more examples, see Mark Levine's books.

EDIT: re-visiting the question, we cannot answer properly, as we are not told which note/s come before and after the A#/Bb. Can the OP enlighten us?

But, the broad answer is keep to sharps in a sharp key, flats in a flat key. The reader is already wearing a matching hat.

  • On your last point, do you want to see D♭ in place of C♯ in a D minor piece?
    – badjohn
    Jun 13, 2019 at 8:07
  • @badjohn - ooh, very good point ! Although, I'd try to argue that any player who knew a bit would expect that note to be C# in key Dm. Minors are somewhat of an enigma. And there will be a place for a Db in a piece in Dm - just trying to find it!
    – Tim
    Jun 13, 2019 at 8:11
  • It's one of these things that is obvious to the experienced person but hard to codify exactly.
    – badjohn
    Jun 13, 2019 at 8:21
  • @badjohn - that's probably what makes this an intriguing question!
    – Tim
    Jun 13, 2019 at 8:26
  • 1
    @badjohn - the C# in key Dm comes about from a different 'rule' that says there needs to be only one of each letter name in the appropriate scale, thus Db wouldn't fetaure. But that's all blown apart whe considering Blues scales, which by definiton will *have8 to have two notes of the same name, therefore occupying the same place on a stave. Awkward - make one 'rule' and another gets broken...
    – Tim
    Jun 13, 2019 at 9:08

I assume that this question arises because you're composing on a fixed-pitch instrument, tuned in 12-tone equal temperament, without distinction between enharmonic notes. Probably a piano.

For convenience, I shall denote the 12 notes of the chromatic scale with the integers modulo 12, using the convention that 0=C, 2=D, 4=E, 5=F, 7=G, 9=A, and 11=B; with 1, 3, 6, 8, and 10 being black keys.

The E (natural) minor scale consists of the notes E (4), F♯ (6), G (7), A (9), B (11), C (0), and D (2). Your bassline includes note 10 and you need to decide whether to notate it as A♯ or B♭ (or maybe even C𝄫).

Or more generally, how to denote the 5 chromatic notes that are not part of the diatonic E-minor scale.

  • Is note 1 C♯, D♭, or B𝄪?
  • Is note 3 D♯, E♭, or F𝄫?
  • Is note 5 E♯, F, or G𝄫?
  • Is note 8 G♯ or A♭?
  • Is note 10 A♯, B♭, or C𝄫?

Approach #1: Match the key signature

You already have a sharp in your diatonic scale, so just use sharps for the 5 chromatic notes: C♯, D♯, E♯, G♯, and A♯.

For note 5, you could choose to use F instead of E♯, but since you'd have to write an accidental (♮) anyway to unsharpen the F♯, there's no notational advantage in doing so.

Approach #2: Tertian harmony

The popular types of chords in Western music are all built out of thirds: M3 (4 semitones) and m3 (3 semitones). There are 3 possible ways to reach note 10 from the E-minor scale and thirds:

  • F♯ (6) + M3 (4) = A♯ (10)
  • G (7) + m3 (3) = B♭ (10)
  • D (2) - M3 (4) = B♭ (10)

So if, for example, you intend this note to be the middle of a F♯-major chord (F♯ + A♯ + C♯), spell it as A♯. If, OTOH, it's part of a G-minor chord (G + B♭ + D), spell it as B♭.

Approach #3: Circle of Fifths

Assume that notes closer together on the Circle of Fifths are more consonant or otherwise “better” when played together. (For now, let's not debate whether this is actually true.)

The Circle of Fifths order of notes, with the E-minor scale in brackets, is:


For note names as close to the bracket diatonic scale as possible:

  • Note 1 = C♯, only 1 fifth outside the scale (vs. D♭ which is 5)
  • Note 5 = F♮, also only 1 fifth outside the scale (vs. E♯ which is 5)
  • Note 8 = G♯, 2 fifths outside the scale (vs. A♭ which is 4)
  • Note 10 = B♭, 2 fifths outside the scale (vs. A♯ which is 4)
  • Note 3 is a tie between D♯ and E♭, each 3 fifths outside the scale. Break the tie by noting that it's far more common to raise the seventh note in a minor scale (as in harmonic and melodic minor) than the lower the first. So D♯.

The full E-minor chromatic scale in order is thus:

E, F♮, F♯, G, G♯, A, B♭, B, C, C♯, D, D♯, E

Or, using moveable-do solfège with the la-based (relative) minor convention:

la, ti♭ (te), ti, do, do♯ (di), re, mi♭ (me), mi, fa, fa♯ (fi), sol, sol♯ (si), la

  • 1
    My problem with Approach 1 is that it confuses accidentals as notes (i.e., non-naturals) with accidentals as signs (including ♮). Even when mechanically counting the symbols needed, the end result depends on total context, and raising or lowering the tonic can easily end up disadvantageous. On the other hand, Approach 3 adds an important point not seen in the other currently available answers. Jun 14, 2019 at 16:16

It is strange to me that the emphasis of answers to this question are on the theoretical "correctness" of notation. Yet, what is truly most important is your intent when writing something down. Once notated parts are performed, the resulting sounds are completely unaffected by the way in which they were notated.

Does a Bb sound different from an A#?

...which leads to the question: Why should I notate something one way or another?

The answer is actually quite simple! What is clear? What is concise? If you read it, is it confusing? When you get someone else to read it, does it make sense to them?

Theoretically I could write a piece in E# major but how would that change the way it sounds compared to writing it in F? Theory is only a way to bridge our individual experiences of sound. It can be useful... Just don't forget that music doesn't actually exist, and that whatever achieves your intent is what really matters.!

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