One thing common to jazz but found less often in other styles of music is chord substitutions. In its simplest form, this is the process of playing one chord instead the one originally specified in order to spice up the harmony, create different voice leading, or take the song in a different harmonic direction.

If you are familiar with jazz you very well may have heard people talk about the “tritone substitution.” If you are versed in general music theory, you most likely have heard of “relative” major or minor chords and keys. Both are examples of simple chord substitutions.

Today we’re going to explore these substitutions and a few others to give you some ideas, inspiration, and ammunition for your next jam session or songwriting endeavor. Although these examples may seem very “jazzy” by nature, I strongly suggest you see how you can apply them to whatever style of music you are playing.

Simple Substitutions

Let’s say you have a chord progression that has a CMaj7 chord in it. The notes of a CMaj7 chord are C, E, G, and B.

There it is, all nice and big so you can see it clearly. Now, if we were to add another diatonic note to the chord we would get a CMaj9 chord:

If you take the bottom note – ‘C’ – out of the equation, you end up with the notes E, G, B, D:

Interestingly, the notes E, G, B, and D make up an Em7 chord:

With this in mind, when you come across a CMaj7 chord and want to change things up slightly, you can substitute the CMaj7 with an Em7 chord. Since the bass player usually covers the root of the chord, there is no need to play it as well, so an Em7 would sound great as a sub.

Now, if you’ve been working this out in your head, you might think that you can pretty much substitute any chord from the C Major scale and play it instead of the CMaj7. Technically, yes, you can. If you are looking to get completely adventurous you can substitute any chord you want. Just try to keep in mind the context in which you are playing. If you’re writing your own song, by all means go to town! But, if you’re comping behind a soloist at a jazz gig, more often than not you’re going to want to keep it somewhat simple and not overwhelm the improviser that you are backing up.

Dom7 Chord Sub

Let’s take a very common jazz progression, the I-vi-ii-V. Here it is in the key of C Major:

What we can do here is tweak the Am7 a little bit to help it lead to the Dm7. We do this by raising the ‘C’ one half step to ‘C#’, which turns the Am7 into an A7 chord:

This gives the progression a sense of being pushed slightly and gives the improviser something more interesting to work with. All of the possibilities for playing over a Dom7 chord now apply.

If we wanted, we can apply the same type of chord substitution to the Dm7 chord, making it a D7 chord so it leads better to the G7.

Personally, I don’t like to use this very often. It’s a bit of overkill, in my opinion. But the logic is sound and once you understand the principle you can inject into your playing whenever you want.

With this, you can also use the “simple substitution” principle I explained at the beginning. You can substitute an Em7 for the CMaj7:

(I kept the D7 in just for the heck of it.)

A lot of times when there are two I-vi-ii-V chord progressions from the same key in a row, the person comping will use I-vi-ii-V for the first four-bar phrase, and then iii-vi-ii-V for the second.

The Tritone Substitution

This is the Holy Grail of subs for jazz. Some people have a hard time grasping this at first, so I’ll do my best to explain it simply.

Let’s stay in the key of C Major. To resolve to the CMaj7 chord we generally want to play a G7 chord. The notes of the G7 are G, B, D, and F. Take a look at the relationship between the notes B and F, the 3rd and 7th notes of the chord. These are considered to be the “most important” notes, since they are the ones that truly determine the color and type of chord being played. These two notes are the interval of a tritone apart.

Now, what we want to do is flip these two notes around, making the B the 7th and the F the 3rd. Is there a chord you can think of that has those notes in those positions?

Think harder; it’s a little bit tricky, but you can get it if you concentrate.

Give up? Okay, I’ll tell you: the chord that has B as the 7th and F as the 3rd is a Db7 chord. The trick here is to remember that the 7th of Db is Cb, which is enharmonically the same as B.

Db, F, Ab, Cb(B)

They are the same exact two notes, just flipped around. So now, if we wanted we can substitute a Db7 for the G7. Here’s an example:

Instead of the G7, we’re playing a Db7. What’s also very cool about this substitution is the root movement of the chords. It’s a nice 1/2 step to 1/2 step movement from Dm7 to CMaj7, but we keep all of the benefits of the G7 sound because of the notes B and F. Gotta love it!

I hope that was easy enough to understand. Another way to think of it would be to just play a Dom7 chord one 1/2 step up from the root of the chord you’re going to. If the chord is AMaj7, you’ll play a Bb7 as a sub for the E7.

We’ll cover more substitutions at some point down the road, but this should keep you busy for a little while.

Enjoy!