So you’re writing or editing, and you come across a word in the middle of a sentence that stops you: “so.” A lot of people assume they should always put a comma before “so” because it’s a conjunction. Others don’t ever use a comma. However, there’s a time and a place for both.
In today’s Grammar Time, we’re discussing when to use a comma before the word “so.”
When to Use a Comma
A comma is needed before “so” when it’s acting as a conjunction to bring together two independent clauses. An independent clause is a complete thought with its own subject and predicate. In this situation, each clause is equal in weight, and neither clause is dependent on the other to make sense.
When Not to Use a Comma
A comma is not needed before “so” when it’s followed by a dependent clause and includes an often-implied “that” (he did something so that something else would happen). Though this clause may also have its own subject and verb, its meaning is dependent on what precedes “so.” You can also try replacing “so” with with the phrase “in order that.” Something happens in order that (or so that) something else will happen. If “so that” or “in order that” makes sense in the sentence, the clause is dependent and there shouldn’t be a comma.
Examples of Both
The teacher was sick, so the test was canceled. — Independent, comma.
The student pretended to be sick so he wouldn’t have to take the test. — Dependent, no comma.
Our team offers same-day services, so call us today to get started. — Independent, comma.
Our team offers same-day services so you can get back to your normal, day-to-day life. — Dependent, no comma.
How to Determine Whether to Use a Comma
An easy way to figure out if there should be a comma is to replace the “so” with “so that.” If “so that” makes sense, the following clause is dependent and there should not be a comma.
For instance, using the first example, try replacing “so” with “so that”: “The teacher was sick so that the test was canceled.” Unless the teacher became sick in order for the test to be canceled, “so that” doesn’t work in this context, so a comma is necessary.
In contrast, try the same thing in the second sentence: “The student pretended to be sick so that he wouldn’t have to take the test.” Here, it’s clear that the student pretended to be sick in order that he wouldn’t have to take the test, making the clause dependent and removing the need for the comma.
Another way to determine whether or not to use a comma is to split the sentence into two and replace the “so” with a period. If the two sentences work on their own, then the original sentence requires a comma because the two clauses are independent of each other. If the new sentences don’t make sense on their own, then don’t use a comma because the second clause is dependent on the first clause.
Let’s try this with our second set of examples: “Our team offers same-day services. Call us today to get started.” Here, you can see that each sentence can stand on its own, and everything makes sense when read together. Therefore, a comma is required when the clauses are combined into a single sentence.
Now, try the same thing with the next sentence: “Our team offers same-day services. You can get back to your normal, day-to-day life.” Can you sense that something’s missing? The second sentence doesn’t feel complete or totally relevant when read together with the first sentence. We’re missing context and connection that the “so” brought. Because of that, there should be no comma.
Still not quite getting it? Pull up an online article and find a few sentences with “so” in the middle so you can practice. (See? That sentence just used a dependent “so.”)