Borrowed chord

Every major key has a parallel minor, the minor key on the same home note. C major (C D E F G A B) and C minor (C D Eb F G Ab Bb) share their tonic but differ in three notes, and each has its own seven chords. A borrowed chord is one of the minor key’s chords used in the major key, or the other way around. Theory books call the habit modal interchange or modal mixture.

These are the loans you will hear most in C major, all from C minor:

The easiest one to hear is the minor iv. Play C, F, Fm, C slowly. From F to Fm, one note drops a half step, A to Ab, and then Ab slides down to G in the C chord. The mood turns from warm to bittersweet in a single move. Ab, Bb, C (bVI, bVII, I) sounds bright instead: the roots climb a whole step at a time into the home chord, which makes a big, triumphant ending.

Borrowing works the other way too, from major into minor. A piece in A minor that ends on A major, with C# in place of C, borrows the tonic chord of A major. Composers from the Renaissance through Bach’s time ended minor-key pieces this way so often that it has its own name, the Picardy third. Chords can also come from other modes that share the home note: Bb is the bVII of C Mixolydian as well as a chord of C minor, which is one reason rock uses it so freely.

A beginner usually meets a borrowed chord as the one chord in a song that is not in the key, like an Fm on a chord chart full of C, F, G and Am. It is there on purpose. The chords in C minor page shows all seven chords you can borrow into C major, and the sad chord progressions list has two built on the minor iv.