Learn English – Do you need a comma before a subordinating conjunction (like if)

commas

Are both of the following sentences correct?

a: You can call me, if you need me. OR
b: You can call if you need me.

Note that in a:, the comma is placed before the "if" and is not present in case b.

From this link, I gather that it isn't necessary because it's a short sentence: Is it mandatory to use a comma before a coordinating conjunction uniting the two independent clauses in a compound sentence?

But can someone point out an "official" source on this usage?

Best Answer

The question that you brought up wouldn't address your question because "if" is not one of the coordinating conjunctions, but it is a subordinating conjunction. The words that introduce each are:

Coordinating Conjunctions: and, but, or, yet, for, nor, so (a helpful acronym is FANBOYS)

Subordinating Conjunctions: after, although, as, as if, as long as, as though, because, before, even if, even though, if, if only, in order that, now that, once, rather than, since, so that, than, that, though, till, unless, until, when, whenever, where, whereas, wherever, while

The definition of a subordinating conjunction is:

Subordinating Conjunction (sometimes called a dependent word or subordinator) comes at the beginning of a Subordinate (or Dependent) Clause and establishes the relationship between the dependent clause and the rest of the sentence. It also turns the clause into something that depends on the rest of the sentence for its meaning.

He took to the stage as though he had been preparing for this moment all his life.

Because he loved acting, he refused to give up his dream of being in the movies.

Unless we act now, all is lost.

This article from Purdue on coordinating and subordinating conjunctions explains the usage of the subordinating conjunction as follows:

Notice that when the subordinate clause comes at the beginning, it’s necessary to insert a comma.

From this, the correct punctuation of "You can call me if you need me" is:

You can call me if you need me.

If you were to move the subordinating conjunction to the beginning, however, you would need the comma as follows:

If you need me, you can call me.