How to Write the Subject Line of a Business Letter

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If you study the structure of a letter, you will find different important parts in it. You may find some parts confusing or want to know more about them. I have been teaching business writing for a couple of years, and I find many of my students utterly confused about a letter’s subject line.

The subject line of a letter must be short, specific, and placed between the Salutation and the Body of the letter. You can write a subject line in uppercase or boldface, and if the emphasis is required, it can be aligned center. The subject line of a letter helps the recipient understand what the letter is about.

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In your professional life, you must write business letters for different purposes in many situations. Whether you apply for a job or terminate someone from his or her position, the professional world’s usual practice is to communicate by writing a letter.

The questions that I frequently experience are, “Is it mandatory to write a subject line? Why do I need a subject line? Do I need to write a complete sentence as a subject line? Where should I put the subject line? Which format should I follow—British or American?” and the like.  

If you also have such questions, no worries. In this post, I will discuss the ins and outs of a business letter’s subject line. Later in this article, I will also briefly discuss the different types of business letters and their purpose.  

What Is a Subject Line of a Business Letter

The subject line of a letter indicates the letter’s purpose in a very short and simple way. By reading the subject line of a letter, the receiver can understand what the letter is about. She or he does not even need to read the whole letter. When you write a business letter, you must consider that your reader does not have that much time, and she or he will just skim the letter.

Well! Here is a book, E-Mail Subject Line Brainstorm: 901 Field-Tested E-mail Subject Lines That Get Your E-mails Opened (Amazon Link) to help you write amazing subject lines. You can have a look at it.

Sometimes, only skimming the letter may make it difficult to have a clear idea about the letter’s purpose. A subject line can make this job easy. Just reading the subject line (a few words, not even a complete sentence), one can clearly understand the issue of the letter. Here are two business letter formats that show two possible positions of the subject line.

In the Sample Business Letter Format 1, the subject line is between Inside Address and Salutation, while in the Sample Business Letter Format 2, the subject line is after the salutation and before the body of the letter.

[Sender’s Address


[Inside Address

[Subject Line



[Complementary Close

[Signature & the Printed Name of the Sender

Sample Business Letter Format 1
[Sender’s Address


[Inside Address


[Subject Line


[Complementary Close

[Signature & the Printed Name of the Sender

Sample Business Letter Format 2

Do You Really Need a Subject Line in a Business Letter?

Many business professionals think that the subject line is not essential. Yes, it is not mandatory, but using a subject line may greatly help to have easy and sound communication through a business letter. Though many out there consider a subject line as an optional part of a business letter, I would like to recommend writing a subject line in a business letter.   

Suppose the letter is too short, and the receiver can immediately understand reading it. In that case, you may not need a subject line. But if you still want to put a subject line, it is good. However, if the letter is comparatively long and details any issue, you should add a subject line. It will help your receiver to understand the purpose of the letter in a short time.

Where to Put the Subject Line in A Business Letter

As a letter has different parts, you may get confused about which part you should put at the beginning, which is in the middle or end. You can have a look at the Sample Business Letter provided in the above part of the post.

The ideal place to put a subject line is between the Salutation and the Main Body. You can also put the subject line between Inside/Receiver’s Address and the Salutation. However, you can keep a blank line before and after the subject line to increase readability.

Dear Mr. Jason, [Salutation]

Subject: Invoice no. 3522 [Subject Line]

With reference to the above invoice… [Body]  
Sample 1: Placement of a Subject Line
Subject: Invoice no. 3522 [Subject Line]

Dear Mr. Jason, [Salutation]

With reference to the above invoice… [Body]  
Sample 2: Placement of a Subject Line

How Should a Subject Line Be in A Business Letter

There are some common methods of writing the subject line of a business letter.

  • Write “Subject:” and then mention the subject of the letter.
  • Use “Re:” instead of “Subject:” if you write to correspond with a large company. “Re” refers to “Reference,” which is also used for legal correspondence. When you use “Re:” it means you are using a “Reference Line,” not a subject line. Yet, both the Subject Line and Reference Line serve the same purpose.
  • Use UPPERCASE or Boldface to write the subject line.
  • Keep left-aligned or centered (on special occasions where more emphasis is required).
  • Keep a blank line before and after the subject line.

Crafting a clear and appropriate subject line for business correspondence is crucial as it sets the first impression and guides the recipient on the letter’s content. Here are examples of subject lines for different types of business letters, which are very common in business correspondence.

  1. Acknowledgment Letter
    • Subject: Acknowledgment of Order No. 12345
    • Subject: Receipt Confirmation of Your Email Dated [Date]
  2. Appointment Letter
    • Subject: Official Appointment to the Position of [Job Title]
    • Subject: Confirmation of Your Appointment as [Job Title]
  3. Apology Letter
    • Subject: Sincere Apologies for [Issue/Incident]
    • Subject: Apology for Service Delay on Order No. 12345
  4. Complaint Letter
    • Subject: Complaint Regarding Defective Product [Product Name]
    • Subject: Service Quality Concern – Customer ID 67890
  5. Inquiry Letter
    • Subject: Inquiry About [Product/Service Name] Features
    • Subject: Request for Information on [Topic/Subject]
  6. Job Application Letter
    • Subject: Application for [Job Title] – [Your Full Name]
    • Subject: [Your Full Name] – [Job Title] Application
  7. Order Letter
    • Subject: Order of [Quantity] Units of [Product Name]
    • Subject: Placement of New Order – Order No. 78910
  8. Resignation Letter
    • Subject: Resignation Notice – [Your Full Name]
    • Subject: Notice of Resignation Effective [Date]
  9. Recommendation Letter
    • Subject: Letter of Recommendation for [Employee’s Name]
    • Subject: Professional Recommendation – [Employee’s Name]
  10. Sales Letter
    • Subject: Exclusive Offer for [Product/Service Name]!
    • Subject: Introducing Our New [Product/Service] – Act Now!

Each subject line is tailored to give a quick insight into the letter’s content, ensuring the message’s purpose is understood at first glance.

British vs American: Subject Line of Business Letters

The subject line of a business letter is a crucial element as it guides the recipient to the letter’s main content and sets the tone for the communication. British and American English have subtle differences in business correspondence, including how subject lines are crafted. Here’s a guide to understanding these variations:

British English Subject Lines

Embracing the subtleties of British formality can set the tone for respectful and professional dialogue. When drafting a subject line in British English, it’s not just about what you say but how you say it, encapsulating tradition and politeness in just a few words.

  • Formality: British English often leans towards formality, favoring traditional and polite expressions.
  • Style: The style is understated, with an emphasis on clear, concise communication without being overly familiar.
  • Spelling and Grammar: British spelling and grammatical conventions should be followed (e.g., ‘Sincerely’ instead of ‘Sincerely’).
  • Example Subject Line: “Subject: Request for Extension of Credit Terms”

American English Subject Lines

American business communication often breaks through formality to deliver a clear point with efficiency. A subject line in American English gets straight to the heart of the message, mirroring a culture that appreciates brevity and a conversational approach.

  • Formality: American English tends to be more direct and less formal, especially in less conservative industries.
  • Style: The style is straightforward, getting to the point quickly and using a more conversational tone.
  • Spelling and Grammar: American spelling and grammatical conventions are used (e.g., ‘Favor’ instead of ‘Favour’).
  • Example Subject Line: “Subject: Credit Terms Extension Request”

Key Considerations for Both

Regardless of the cultural context, certain principles hold true when penning the perfect subject line. Clarity, relevance, and brevity are the keystones of any effective business communication, ensuring that your intention is understood at a glance.

  • Clarity: Both British and American business letters prioritize clarity, ensuring the subject line accurately reflects the letter’s content.
  • Relevance: The subject line should be relevant to the recipient, addressing their interests or the nature of your relationship.
  • Brevity: It should be concise, ideally under 10 words, to quickly convey the message.

Cultural Nuances

Navigating the cultural landscapes of British and American English can be as intricate as the business dealings they facilitate. Understanding these differences is crucial; a subject line that resonates in one culture may not hold the same weight in another.

  • British Formality: In British English, there might be a greater use of polite language, even when making direct requests or statements.
  • American Directness: American business culture values directness and getting to the point, which is reflected in the subject lines.

When writing subject lines for an international audience, consider the following tips:

  • Know Your Audience: Adapt your language according to the recipient’s expectations and the usual practices in their business culture.
  • Be Specific: Whether British or American English, ensure your subject line clearly states the topic or the action required.
  • Cultural Sensitivity: Be mindful of cultural differences in communication styles; what is considered polite and formal in one culture may be considered overly stiff in another, and vice versa.

Remember, while these are general guidelines, the context of your letter and the industry can also influence how formal or direct your subject line should be. Always tailor your communication to fit the situation and your relationship with the recipient.

How Important Is Business Letter in Business Writing

Business letters are a foundational element in the vast landscape of business writing. In a digital age where communication often happens at the click of a button, the importance of business letters remains high due to their formal and professional nature. These documents carry a sense of gravitas and formality that digital communications often lack, making them indispensable for certain types of professional correspondence.

Letters serve various functions in business operations, including making inquiries, registering complaints, acknowledging transactions, and confirming agreements. For instance, if a consumer needs detailed information about a product, such as a laptop from HP, an inquiry letter allows for a formal request that clearly states the required information like price, specifications, and availability. This not only ensures that the request is taken seriously but also provides a documented trail that can be referenced later.

Similarly, when addressing issues with a product, such as a defect in a Samsung item, a complaint letter serves as a formal method of expressing dissatisfaction, allowing the company an opportunity to address the concern directly. This formal approach can often be more effective in eliciting a response and action from a company compared to an informal complaint.

Joining a new company also involves formal communication, often in the form of a joining letter, which formally acknowledges and accepts the offer of employment. This letter becomes a part of the employee’s official record and lays the foundation for the employment terms and relationship.

In the realm of business writing, which encompasses emails, memos, proposals, reports, press releases, and resumes, business letters stand out for their formal structure, clear intent, and the official nature of their content. They are an essential component of professional etiquette and serve as a testament to the enduring value of formal written communication in conducting business effectively.

The table shows different common types of business letters and their purpose.

Letter TypePurpose
Acknowledgment LetterTo confirm something—confirm receiving an order, acknowledge mistakes, and inform the receiver that their previous messages have been received.
Appointment LetterTo affirm that the employee has been selected for the position she or he has applied for.
Apology LetterTo ask for forgiveness.
Complaint LetterTo complain about any product or service.
Inquiry LetterTo inquire about something.
Job Application LetterTo provide information about the qualifications, skills, and experience and apply for the vacant position.
Order LetterTo order products or services from a supplier or a seller.
Resignation LetterTo officially inform the authority that you want to quit the job.
Recommendation LetterTo recommend an employee to another company.
Sales LetterTo introduce your business to potential customers and request to take action.

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Final Thoughts

When you write any business letter, you must consider that your reader has limited time. You should not make your letter too long with unnecessary words. Your audience expects you to talk directly about the matter and clarify the letter’s purpose. You can have the following parts in your business letter. They must appear in the letter according to the following order.

  1. Sender’s Address
  2. Date
  3. Inside/Receiver’s Address
  4. Salutation
  5. Subject line
  6. Body
  7. Complimentary Close
  8. Signature & Printed Name of the Sender
  9. Enclosure (If Any)

Frequently Asked Questions

Why is the subject line important in a business letter?

The subject line quickly informs the recipient about the letter’s main topic, ensuring they understand its purpose and importance, which can prompt timely action or response.

How long should the subject line be?

Ideally, keep the subject line concise and to the point, typically between 4 to 8 words, ensuring it captures the essence of the letter’s content.

Where should the subject line be placed in a business letter?

The subject line is usually placed below the salutation and before the main body of the letter, and it’s often underlined or bolded for emphasis.

Should I use full sentences or phrases for the subject line?

Phrases are generally preferred as they are more concise. Avoid using full sentences; instead, get straight to the point with clear, descriptive terms.

Is it necessary to use the word “Subject” before the actual subject line?

While it’s not mandatory, using the word “Subject” or “Re” (short for “Regarding”) before the subject line can provide clarity.

Can I use abbreviations in the subject line?

Only use widely recognized abbreviations relevant to the business context. Avoid using slang or lesser-known abbreviations that might confuse the recipient.

How formal should the subject line be?

In a business letter, it’s best to maintain a formal tone. Avoid casual or colloquial language unless you’re certain it’s appropriate for the recipient and the context.

Should I capitalize the entire subject line?

No, it’s best to use title case, capitalizing the first letter of each principal word. Avoid using all caps as it can come across as shouting or aggressive.

What if my subject line is too long and doesn’t fit on one line?

If the subject line extends beyond one line, break it at a logical point, ensuring it remains readable and maintains its impact.

How can I make sure my subject line grabs the recipient’s attention?

Keep it relevant, clear, and direct. If the letter is about a critical issue or requires urgent action, make sure the subject line reflects the urgency without sounding alarmist.

If you have further questions or suggestions about anything specific related to this topic or anything else related to learning English as a second language, feel free to ask me in the comment box. You may also help the ESLA community by putting your valuable suggestions here to help every member improve their English language skills.

Niaj A A Khan is an ESL Instructor with over 8 years of experience in teaching & developing resources at different universities and institutes. Mr. Khan is also a passionate writer working on his first book, "Learn English at Ease."

1 thought on “How to Write the Subject Line of a Business Letter”

  1. Great post! I totally agree that the subject line is crucial in grabbing the reader’s attention and making them want to open the letter. I’ve found that using a clear and concise subject line that relates to the main message of the letter can make all the difference in getting a response. Thanks for the tips!

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