What Is the Subject Line in a Business Letter?

The subject line of a business letter is the portion of the letter where you tell the reader about your subject. Although a subject line is not always necessary in a business letter, especially if the letter is brief, it can be helpful, as it immediately conveys to the reader the subject of the letter.

Placement

The subject line of a business letter is often placed at the very top of the letter, or directly under the subject's name. In some instances, the subject line is also placed in line with the subject's name, justified to the right. Subject lines are generally identified by use of the terms "Re:,” which means “In regards to,” or just “Subject.”

Content

The content of a subject line should be very short and to the point. Common examples of information used in subject lines include a reference number associated with an order, a number associated with a case file, or a date and a corresponding event. Avoid lengthy subject lines, as they will detract from the body of your letter.

Omission

If you are writing to a company that you do not anticipate having routine correspondence with, or if you are writing a very brief letter, you may omit a subject line. However, if you are replying to someone's letter or writing about a specific transaction or invoice number, you should use a subject line. In the above instances, use of a subject line can result in the writer receiving a quicker response.

Other Components

The other components of a business letter include the addresses of the sender and receiver, the date, the greeting, the body of the letter, the closing, and the enclosures line and the typist's initials, when applicable. Crafting a business letter with an appropriate subject line and the other necessary components will make your correspondence with the other party appear professional.