Borrowed Chords
A chord borrowed from the parallel major or minor key

The most common usage is to borrow chords from the parallel minor to be used in the major
The altered scale degrees to look for are the minor 6th (most common) and the minor 3rd
The most common borrowed chords (in the major) are iv, iiº, bVI, and i
The iv, iiº, and bVI have the minor 6th scale degree
The bVI and i have a minor third scale degree
The most common borrowed chord in a minor key is the I
Usually seen at the end of a piece
Usually referred to as having a “picardy” third

A possible borrowed chord, but one not commonly seen is the bIII in a major key
Borrowed chords generally resolve as they would in their initial mode, following strong root movements
down a 5th / down a 3rd / up a 2nd
Care should be taken when resolving the altered pitches
Altered pitches tend to continue (resolve) in the direction they are altered