Third Party or Third-Party?

The term third party without a hyphen is a noun that refers to another person. E.g., “A third party must sign the contract as a witness.” Furthermore, the hyphenated version, third-party, is an adjective. Therefore, it always describes a noun. E.g., “My insurance only covers third-party drivers.”

The word third party refers to another person or people who are additional to the two parties involved in a dispute, process, or situation.

The grammar rule states that whether or not to use a hyphen depends solely on the word type of third party in your sentence.

Thus, you do not use a hyphen when the term third party is a noun that refers directly to the other party.

For example, in this sentence, we refer directly to the person who will assess the job. I.e., the third party.

  • I would like to get a third party to assess the job and give me their quote.

In contrast, if third-party describes a noun, it is a compound adjective rather than a noun. In these cases, you need a hyphen.

For example, in this sentence, the word third-party describes what type of assessment will be done. I.e., an assessment by a third party.

  • I would like to get a third-party assessment and quotation for the job.

In addition, if you are writing a text in AP Style or following the Chicago Manual of Style, you should use the above guidance concerning the use of a dash with third party.

Furthermore, writing thirdparty as a single word without a hyphen or space is not a correct spelling version of the term.

Now you have seen the basics concerning the term third party. Please keep reading to learn more about using the different forms in your writing.

Third Party

The term third party as two words with no hyphen is a noun that you use to refer to an additional person or people who are external to a particular process.

This is also the more popular way to write the term in the UK and the US. However, it is probably more common because using the noun is more common than the adjective, rather than people having a specific spelling preference.

You will know when not to put the hyphen because there will be no noun that the term third party modifies.

  • I want a third party to be present when we sign the contract.
  • We’ve decided to hire a third party for an unbiased review of the situation.
  • It’s essential to have a third party mediate in disputes to ensure fairness.
  • The negotiations reached a point where both sides felt a third party was necessary for resolution.

In the above sentence, the third party represents the person rather than describing the person. Therefore, there is no hyphen.

You can also use the term third-party in the plural form. Take a look at this example, in which the third parties are businesses:

  • Third parties sell our cosmetics, and we have no contact with the clients.
  • To expand our market reach, we collaborate with third parties to distribute our products.
  • Be cautious when sharing personal information online; it might be accessed by third parties without your knowledge.
  • The app allows third parties to develop plugins, enhancing its functionality.
  • Our company’s data policies prohibit sharing user data with third parties unless explicitly agreed upon.


The term third-party, as one word with a hyphen, is a compound word that you can use to indicate that a noun is external or additional to a particular process.

You can identify whether to use a hyphen by determining whether a third party is modifying a noun.

For example, in the first sentence, we know that the lawyer is not my lawyer and that they represent a third party.

  • A third-party lawyer contacted me and said my lawyer was guilty of malpractice.

Also, in the below sentence, the term third-party describes that the damage, in this to a car, belongs to someone else.

  • My insurance is not paying for the third-party damage, so I have to pay for it myself.

Here are some more examples that should help you understand how to use third-party in a sentence:

  • We had to involve a third-party mediator to help resolve the dispute between the two teams.
  • For additional security, the company uses a third-party service to handle all financial transactions.
  • Before downloading the software, I was warned about potential third-party ads that might pop up.


The term thirdparty as one word with no space and no hyphen is incorrect. However, there are two correct spelling versions of the term third party.

The first is without the hyphen, in which case the third party is a noun.

  • Correct: We need to ask a third party before committing to a decision. (noun)
  • Incorrect: We need to ask a thirdparty before committing to a decision. (noun)

The second way to write the term is with a hyphen, in which case third-party is an adjective.

  • Correct: We need to consult a third-party consultancy firm for their opinion. (adjective)
  • Incorrect: We need to consult a thirdparty consultancy firm for their opinion. (adjective)