bVI

bVI is a roman numeral used in music theory to denote a major triad built on the flattened sixth scale degree of a key. It is a non-diatonic chord in major keys and is typically borrowed from the parallel minor through modal mixture. For example, in the key of C major, the sixth scale degree is A, and the bVI chord is Ab major (Ab–C–Eb). The label bVI signals that the root is a semitone lower than the diatonic sixth degree.

In practice, bVI is most commonly encountered as a coloristic, borrowed chord in popular, rock, and folk music. It provides a bright, unexpected color that can lead smoothly to IV or I, or move to bVII or V in certain progressions. Common progressions include bVI–IV–I or bVI–V–I, among others. The chord often serves as a strong chromatic preface to the tonic, creating a sense of expansion before resolution.

Voice-leading and notation considerations emphasize that the bVI chord is major, reflecting its derivation from modal interchange rather than diatonic harmony. The chromatic root movement from the flattened sixth degree to diatonic targets (such as IV, V, or I) yields characteristic color without requiring complex extensions. Beyond pop, the concept also appears in various forms of jazz and film music as a borrowed-submediant color.

See also: borrowed chords, modal mixture, parallel minor, bVII.