Grammar Guides

When To Use A Comma Before “Because” (And When Not To!)

Written by Kieron Moore

Correct comma usage can cause headaches for many writers—even more so when the word “because” is involved. You may have heard the advice that a comma should never come before “because.”

Until recently, any sentence on the SAT test with a comma preceding “because” would automatically be marked as wrong. However, it isn’t fair to apply such strict black-and-white rules. The Chicago Manual of Style disagrees with the SAT system and states that sometimes the comma is needed.

Whether you should use a comma depends on context. Remember, the purpose of grammar is to provide clarity of meaning, so you need to think about how a comma would affect your sentence’s structure and meaning. In this article, we’ll have a look at when you should or shouldn't insert a comma before the word "because".

When "because" is in the middle of a sentence

The word “because” most often appears in the middle of a sentence and is used to introduce a type of dependent clause known as a “clause of purpose.”

In other words, what comes before it is an independent clause—one that could work as a stand-alone sentence—and what comes after it adds explanation.

Consider these example sentences:

Sarah bought a new car because her old one kept breaking down.

John went for a walk because it was a nice day.

In these cases, though adding in a comma would not particularly obscure the meaning, it wouldn’t add anything either, and so the comma is not needed.

Unlike with “as,” which is often used to add less important explanations, “because” is generally used when the explanation, though a dependent clause, is an important part of the information the writer wants to get across. This is why this clause is rarely separated by a comma.


Where the clause of purpose is the main point you want to explain, such as when the purpose of the sentence is to insist that an action was taken for one reason and not for another, it is especially important not to include a comma, in order to place clear emphasis on the clause of purpose.

For example:

John went for a walk because it was a nice day, not because he wanted to get away from his family.

When "because" is at the start of a sentence

An alternative approach is to put the dependent clause at the start of the sentence, followed by the independent clause. In these cases, the sentence starts with “because” and a comma is needed to separate the two clauses.

Let’s rearrange the above examples into this shape:

Because her old car kept breaking down, Sarah bought a new one.

Because it was a nice day, not because he wanted to get away from his family, John went for a walk.

Because of the steaks, I didn’t go to Dan’s restaurant.

These sentences would be very difficult to make sense of without the comma, as two clauses would be joined together without any punctuation or conjunction to separate them.

Putting the subordinate clause first also has the effect of placing more emphasis on that purpose—there is no ambiguity as to why I did not go to Dan’s restaurant.

When to make exceptions

There are some situations where adding a comma before “because” will improve the clarity of the sentence and prevent misunderstanding. This most often occurs when the sentence starts with a negative clause. Look at this example:

I didn’t go to Dan’s restaurant because of the steaks.

One interpretation of this is that I did go to Dan’s restaurant, but the steaks weren’t the most important factor. They’re fine, but it’s something else that drew me there. With this meaning, the sentence could be continued like this:

I didn’t go to Dan’s restaurant because of the steaks, but because of the great selection of wines.

However, what I actually meant in the original sentence was that I did not go to Dan’s restaurant, and the reason I didn’t go was that the steaks are terrible. A comma would help clarify this: 

I didn’t go to Dan’s restaurant, because of the steaks.‍

The comma helps put emphasis on the first clause, clarifying that “I didn’t go to Dan’s restaurant” is the main point and “because of the steaks” is the explanation.


While there is a good reasoning behind the SAT punishing examinees for putting commas before “because,” these exceptions prove that, like many complicated grammatical issues, this advice should be treated as a guideline rather than a strict rule.

In most cases, it is correct not to use a comma before “because.” However, if adding the comma would avoid potential misinterpretations of the sentence, most notably when the sentence starts with a negative statement, then add the comma. And when the sentence starts with “because,” you’re going to need a comma to separate the clauses.

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