Not only but also is an example of a correlative conjunction. That is to say, the conjunction pairs work together to convey meaning. Correlative conjunctions need balance.

The language that follows each part of the conjunction must be parallel. Without balance, your writing becomes tricky to read. Hence, it affects the fluidity of your words.

• Incorrect     The girls not only smart but also has a propensity to be sullen.
• Correct     The girls not only smart but also sullen.

In the above example, both sentences have the same meaning, but they have different constructions. The first sentence is not parallel. Hence, the first sentence follows not only with an adjective and but also with a dependent phrase.

In contrast, an adjective follows each part of the correlative conjunction in the second sentence. The two similar components of speech make the sentence balance and your writing stronger.

Commas usage is another sticky area when it comes to correlative conjunctions. Generally, when drafting a sentence, you want to avoid separating correlative conjunctions with a comma; however, specific circumstances allow for an exception to this rule.

Commas can show emphasis, and because of that, the above rule cannot be without some flux. A comma can separate a correlative conjunction if you want to draw attention to a particular clause. For example:

• When sky diving, Charles focuses on not only his equipment, but also his surroundings.

The commas in the sentence above are not necessary. Instead, they represent a stylistic choice that causes you to focus on a particular detail.

It would also be correct to write the sentences in the following way:

• When sky diving, Charles focuses on not only his equipment but also his surroundings.

Not only but also | Comma Rules

How to Connect “Not only…but also” with a Noun

• My favorite sea creatures are not only sharks but also dolphins and jellyfish.

In this example, “but also” precedes the plural noun “dolphins”. The above sentence does not support the use of a comma.

Rule #1: Avoid using a comma if the correlative conjunction “not only…but also” connects to a noun.

How to Connect “Not only…but also” with a Clause

• Not only will I paint sharks on my wall, but I will also paint dolphins and jellyfish.

This example has a comma placed after “not only” and in front of “but”. A comma comes before the word “but” because the conjunction precedes an independent clause. A comma needs to be applied if the correlative conjunction connects to a specific type of clause.

Independent vs Dependent Clauses

Two different types of clauses can act in a sentence with correlative conjunctions: independent and dependent. Not all clauses operating in sentences with correlating conjunctions need to have a comma interjected into them.

Independent clauses are clauses that can function as a sentence. When the second clause found in the sentence is independent the correlative conjunction “not only but also” will act as a coordinating conjunction. The correlative conjunction not only…but also, more often than not, works as a coordinating conjunction. It is easy to insert a subject after the word “but” and before the word “also”. In contrast, a dependent clause or subordinate clause may have a subject and/or verb but will not represent a full thought. Dependent clauses can be found within independent clauses. They provide additional information to a sentence.

Independent Clause

• Not only will I destroy his crayons, but I will also break his pencils.

The subject “I” can be found between “but” and “also”. This suggests that the second clause is independent. If you are ever unsure about whether a clause is independent or dependent you can remove the word “but” to see if the second clause can form a complete sentence.

Rule #2: A correlative conjunction needs a comma when joined to an independent clause.

Dependent Clause

• Not only will I destroy his crayon but also his pencils.

If you remove the word “but” you are left with “also his pencils.” The second clause is dependent because it needs the first clause to form a complete sentence. In this instance, you would not put a comma in front of the word “but”.

Rule #3: Do not use a comma with a correlative conjunction linked with a dependent clause.

Not only…but also Comma Rules | Summary

• Never use a comma with “not only but also” if connecting a noun.
• Always use a comma when linking correlative conjunctions with independent clauses.
• Never use a comma with “not only but also” if connecting a dependent clause.

Not only but also | Forming Rules

Rule #1: Not only…but also is used in the middle and end of the sentence.

To emphasize the Noun

• S + V + not only + N + but also + N

Examples:

• She is not only an actress but also a singer.
• He is not only a dad but also a mom in the family.

To emphasize the Verb

• S + not only + V + but also + V

Examples:

• She not only read the book but also remembered what she read. 
• She not only writes her own plays but also acts in them. 

To emphasize the Adjective

• S + to be + not only + Adj + but also + Adj

Examples:

• She is not only beautiful but also intelligent.
• Tom is not only rich but also famous. 

To emphasize the Adverb

• S + V + not only + Adv + but also + Adv

Examples:

• Thomas writes not only correctly but also neatly.
• He worked not only hard but also carefully.

Rule #2: Not only…but also is used at the beginning of the sentence.

• Not only does she speak Spanish but she also speaks French.
• Not only you but also I am planning to go.
• Not only do the nurses want a pay increase but they also want reduced hours as well.

Not only but also | Infographic