Knowing where to use a comma before the word “so” is often challenging. Sometimes you need it; other times you should omit it because the context is different.

The comma is the most common punctuation mark and the one people wrestle with the most, particularly when it involves words such as so, when, where, which, and however. Let’s look at so.

The word so serves as different parts of speech, most commonly as a conjunction, which joins two clauses in a sentence.

  • Use the comma when it begins what is a called a clause of result or effect. Here are examples:

 It is difficult to relax during the week, so I like to get away on weekends.

I will be on vacation next week, so please don’t contact me.

  •  Don’t use the comma when you use so that or so to explain why something happened. These are called clauses of purpose:

 We asked for approval early so that we could start on Monday.

The city wanted to tear down the building so the area could become a park.

Some language mavens adhere rigidly to the notion that both words so that are necessary to start the clause, but it has become common to use only so, unless it sounds when you read it that that is necessary.

So is also used as an adverb indicating “to what extent,” as in this sentence: The weather is so hot here or It has become so common.