Learning Objectives
- Distinguish a memorandum from a business letter in terms of purpose, audience, structure, and convention
- Identify the standard components of a memo and apply them correctly
- Determine when to use a memo and when to use a letter in professional contexts
- Recognise and correct common errors students make when confusing the two forms
Topics Covered
- What Is a Memorandum? Definition and Purpose
- Memo Format — Components Explained
- Memo vs Letter — Full Comparison Table
- When to Use a Memo; When to Use a Letter
- Common Errors When Confusing the Two Forms
- Activity: Choose the Right Form
Prerequisite
Lectures 1.1 and 1.2 established the principles of letter writing and the eight components of a business letter. This lecture draws on that foundation to introduce the memorandum as a distinct — and frequently misunderstood — form of professional correspondence.
Section I
What Is a Memorandum? Definition and Purpose
The word memorandum derives from the Latin memorare — to remind. In professional usage, a memorandum (plural: memoranda; abbreviated as memo) is a brief, structured internal document used to communicate information, decisions, instructions, or requests within an organisation (Uwajeh, 2017, p. 112).
Unlike a letter, which crosses the boundary between one organisation and another (or between an organisation and a private individual), a memo travels internally — from one office, department, or officer to another within the same institution. This distinction in audience is the single most important difference between the two forms, and it explains nearly every other difference in structure, tone, and convention that follows (Locker & Kienzler, 2020, p. 183).
Key Distinction
- Letter
- Moves externally — between organisations, or between an organisation and a client, customer, applicant, or member of the public. Requires formal structure, salutation, complimentary close, and full address blocks.
- Memorandum
- Moves internally — between staff, departments, or offices within the same organisation. Dispenses with salutation, complimentary close, and address blocks in favour of a standardised header.
Memos serve a wide range of internal functions: announcing a policy change, summarising a meeting, issuing instructions, requesting information, reporting on progress, or reminding staff of a deadline. What they share is brevity, directness, and a fixed format designed for quick reading and easy filing (Murphy, Hildebrandt, & Thomas, 2018, p. 134).
📌
Simple test: If the recipient works in the same building or under the same organisational structure as the sender, use a memo. If the recipient is outside the organisation entirely, use a letter.
Section II
Memo Format — Components Explained
A standard memorandum replaces the letter's address blocks, salutation, and complimentary close with a compact four-field header. The body that follows is written in plain, direct prose. Below are the components in sequence (Adeyemi, 2021, p. 74).
1
MEMORANDUM Heading
The word MEMORANDUM (or MEMO) appears in bold capitals at the top of the page, centred or left-aligned depending on the organisation's house style. It identifies the document type immediately and distinguishes it from a letter or report.
MEMORANDUM or MEMO
2
TO Field
The full name and job title of the recipient(s). In a memo, the recipient's postal address is never included — the document is internal and will be delivered through internal channels. When addressing multiple recipients, each name and title is listed on a new line.
TO: Mr. Emeka Okafor, Head of Finance
3
FROM Field
The full name and job title of the sender. The sender initials or signs beside their printed name — this serves as authentication in place of the full signature block used in letters. The postal address of the sender is equally omitted.
FROM: Mrs. Adaeze Nwosu, Director of Human Resources
4
DATE Field
The date follows the same convention as in a business letter: day-month-year without ordinal suffixes. The date is essential for internal reference, filing, and establishing when a directive was issued or a decision communicated.
DATE: 15 June 2025
5
SUBJECT Field
A concise, capitalised statement of the memo's topic. The subject line in a memo performs the same function as the subject line in a letter — it allows the reader to grasp the document's purpose instantly. Unlike the letter's "RE:" prefix, the memo subject line often uses "SUBJECT:" or "RE:" interchangeably.
SUBJECT: REVISED LEAVE POLICY — EFFECTIVE 1 JULY 2025
6
Body
The substance of the memo, written in clear, direct paragraphs. A memo body typically opens by stating the purpose in the first sentence, develops that purpose concisely, and closes with a clear statement of what action is required or expected. No salutation precedes the body, and no complimentary close follows it.
This memo is to inform all members of staff that the leave policy for the 2025/2026 financial year has been revised...
Sample Memo
MEMORANDUM
TO:
All Departmental Heads
FROM:
Mrs. Adaeze Nwosu, Director of Human Resources
DATE:
15 June 2025
SUBJECT:
REVISED LEAVE POLICY — EFFECTIVE 1 JULY 2025
This memo is to inform all departmental heads that the organisation's annual leave policy has been revised with effect from 1 July 2025. The key changes are as follows:
Annual leave entitlement for senior staff (Grade Level 12 and above) is increased from 21 to 25 working days per calendar year. All leave requests must henceforth be submitted not less than three weeks in advance using the revised Leave Application Form (Form HR/LA/07).
Please bring this to the attention of all staff under your supervision. Copies of the revised policy document are available from the HR office. Kindly acknowledge receipt of this memo by signing and returning the attached slip.
A. Nwosu
Mrs. Adaeze Nwosu
Director of Human Resources
📐
Memory aid for the memo header: To, From, Date, Subject — "The Four Ds of the Memo Header" or simply TFDS. Every memo must carry these four fields in this order before the body begins.
Section III
Memo vs Letter — Full Comparison
The table below maps the key differences between a memorandum and a business letter across eight categories. Students should study this table closely, as confusion between the two forms is among the most common errors in professional writing assessments (Bovée & Thill, 2021, p. 194).
| Feature |
Memorandum (Memo) |
Business Letter |
| Audience |
Internal — staff, departments, or officers within the same organisation |
External — clients, suppliers, government bodies, applicants, or the public |
| Purpose |
To inform, instruct, remind, or request within an organisation |
To communicate formally across organisational boundaries |
| Format Opening |
TO / FROM / DATE / SUBJECT header (no address blocks) |
Sender's heading, date, inside address, salutation, subject line |
| Salutation |
None — the TO field serves this function |
Required — e.g., "Dear Sir," or "Dear Mrs. Adeyemi," |
| Complimentary Close |
None — the sender's initials or signature beside the FROM field suffices |
Required — "Yours faithfully," or "Yours sincerely," |
| Tone |
Direct, functional, and relatively informal — though still professional |
Formal, structured, and governed by established conventions |
| Length |
Usually brief — one page is standard; rarely exceeds two pages |
Variable — from a single paragraph to several pages depending on purpose |
| Distribution |
Internal channels — hand delivery, internal mail, or organisational email |
External channels — post, courier, or formal email with letterhead |
Section IV
When to Use a Memo; When to Use a Letter
Choosing the correct form is not a matter of personal preference — it is a professional obligation. Using a letter where a memo is appropriate wastes the recipient's time and signals unfamiliarity with organisational convention. Using a memo where a letter is required risks appearing unprofessional and may cause the communication to be disregarded (Olusegun, 2019, p. 143).
Audience
The recipient is a colleague, subordinate, superior, or another department within your own organisation.
Purpose
You are issuing an internal announcement, policy update, meeting notice, progress report, or interdepartmental request.
Urgency
A quick, structured record is needed — one that can be filed, circulated, and acknowledged without the formality of a full letter.
Example
The Head of Finance writes to all departmental heads to announce a budget freeze effective immediately.
Audience
The recipient is outside your organisation — a client, supplier, regulator, job applicant, partner institution, or member of the public.
Purpose
You are applying for something, responding to a complaint, making an offer, issuing a formal notice, or representing your organisation in writing.
Formality
The communication carries legal, contractual, or reputational weight that requires the full formality of a business letter format.
Example
A company's legal officer writes to a supplier to formally dispute a delivery and request a replacement within 14 days.
Section V
Common Errors When Confusing Memo and Letter
The following errors are frequently observed in student assessments and entry-level professional writing. In each case, the writer has applied conventions from one form to the other — a failure that examiners and employers identify immediately (Adeyemi, 2021, p. 81).
| Error Type | What the Student Does | Correct Practice |
|---|
| Salutation in a memo |
Opens the memo with "Dear Sir," or "Dear Mr. Okon," |
A memo has no salutation. The TO field already identifies the recipient. Beginning with a salutation shows the writer has confused the two forms. |
| Complimentary close in a memo |
Ends the memo with "Yours faithfully," or "Yours sincerely," |
A memo has no complimentary close. The writer's initials or abbreviated signature beside the FROM field are sufficient. |
| Inside address on a memo |
Includes the recipient's full postal address in the TO field |
A memo is internal — postal addresses are never included. Only the recipient's name and designation appear in the TO field. |
| Sender's address on a memo |
Writes the sender's postal address at the top of the memo |
A memo needs no heading address. The organisation's letterhead (if used) provides institutional identity; the FROM field identifies the sender. |
| Missing SUBJECT field |
Jumps from the DATE field directly into the body |
The SUBJECT field is mandatory in a memo. Without it, the document cannot be properly filed or referenced. |
| Writing a letter for an internal matter |
Sends a fully formatted letter (with salutation and complimentary close) to a colleague in the same office |
Internal communication — even between senior officers — uses a memo. A letter sent internally is unnecessarily formal and signals an error of judgement. |
Section VI
Activity — Choose the Right Form
Each scenario below describes a real-world communication task. State whether the writer should use a MEMO or a LETTER, and give a brief reason for your choice.
- 1
The Registrar of a polytechnic writes to all academic staff reminding them of the deadline for submitting examination scores.
MEMO — the communication is internal; all parties are staff members of the same institution.
- 2
A student writes to the Lagos State Ministry of Education to apply for a scholarship.
LETTER — the student is communicating externally with a government body outside their institution.
- 3
The Head of Maintenance notifies the Director of Works about a burst pipe in Block C.
MEMO — both parties are officers within the same organisation; the communication is internal and functional.
- 4
A company formally invites another company's Managing Director to a business dinner.
LETTER — the recipient is external to the organisation; a letter is required for formal inter-organisational communication.
- 5
The Accounts Officer writes to the General Manager to request approval for a budget reallocation.
MEMO — although this moves upward in the hierarchy, both parties belong to the same organisation; a memo is the correct internal form.
- 6
A customer writes to an airline to formally complain about a damaged suitcase and demand compensation.
LETTER — the customer is writing externally to an organisation; a formal letter is required to establish a written record for potential legal purposes.
- 7
The Principal of a school circulates new examination timetable changes to all subject teachers.
MEMO — a circular memo is the correct internal instrument for distributing updated schedules to staff.
- 8
A human resources manager writes to a shortlisted job applicant to confirm an interview date.
LETTER — the applicant is external to the organisation and has not yet been hired; external communication requires a letter.
Section VII
Conclusion & Key Takeaway
The memo and the letter are not interchangeable. They serve different audiences, fulfil different functions, and follow different structural conventions. The memo's compact TO/FROM/DATE/SUBJECT header reflects its internal, functional character — speed and clarity within the organisation. The letter's full structure — heading, date, inside address, salutation, subject line, body, complimentary close, and signature block — reflects its external, formal character, representing the organisation to the outside world (Murphy, Hildebrandt, & Thomas, 2018, p. 141).
A professional writer learns to make the choice quickly and correctly: ask first who the audience is. If the audience is internal, write a memo. If the audience is external, write a letter. Every other decision about format, tone, and structure flows from that single question. Together, Lectures 1.1, 1.2, and 1.3 provide the complete foundation for professional correspondence (Locker & Kienzler, 2020, p. 196).
1Multiple ChoiceWhich of the following best describes the primary audience of a memorandum?
A. Members of the public
B. Staff or departments within the same organisation
C. Government regulatory bodies
D. Clients of the organisation
[1 mark]
2List & ExplainList the four header fields of a standard memorandum and state the purpose of each.
[8 marks — 2 per field]
3Multiple ChoiceWhich component is found in a business letter but NOT in a memo?
A. Subject line
B. Date
C. Salutation
D. Body paragraphs
[1 mark]
4DistinguishDistinguish between a memo and a business letter in terms of (a) audience, (b) structure, and (c) tone.
[6 marks — 2 per point]
5Multiple ChoiceA staff member writes to a colleague in the same department about a change in shift schedule. The correct document to use is:
A. A formal letter
B. A memorandum
C. A report
D. A circular
[1 mark]
6Identify the ErrorA student writes an internal memo that begins with "Dear Mr. Eze," and ends with "Yours sincerely." Identify two errors and state the corrections.
[4 marks — 2 per error]
7Multiple ChoiceIn a memo, which field replaces the salutation found in a business letter?
A. SUBJECT field
B. FROM field
C. TO field
D. DATE field
[1 mark]
8ScenarioYour company's Human Resources department wants to inform all employees about a new staff welfare scheme. Write a memo from the HR Director, Mrs. Grace Ekezie, to all staff. Include all four header fields and a brief body of at least two paragraphs.
[10 marks]
9Multiple ChoiceWhich of the following communications would correctly take the form of a business letter rather than a memo?
A. A departmental head notifying staff of a revised work schedule
B. A company writing to a supplier to query an overdue delivery
C. A principal reminding teachers of an examination timetable
D. An accounts officer requesting budget approval from the GM
[1 mark]
10Short Essay"Choosing between a memo and a letter is not a stylistic preference — it is a professional obligation." Discuss this statement, with reference to the distinctions in audience, purpose, and structure between the two forms.
[5 marks]
Adeyemi, T. O. (2021). Professional Written Communication for Nigerian Students (3rd ed.). University of Lagos Press.
Bovée, C. L., & Thill, J. V. (2021). Business Communication Today (15th ed.). Pearson Education.
Locker, K. O., & Kienzler, D. S. (2020). Business and Administrative Communication (12th ed.). McGraw-Hill.
Murphy, H. A., Hildebrandt, H. W., & Thomas, J. P. (2018). Effective Business Communications (8th ed.). Tata McGraw-Hill.
Olusegun, B. (2019). The Complete Guide to Letter Writing and Correspondence. Evans Brothers (Nigeria Publishers).
Uwajeh, M. K. C. (2017). Effective Communication in English for Tertiary Institutions in Nigeria (3rd ed.). Chuka Educational Publishers.
Next Lecture · Module 1
Lecture 1.4 — Portfolio of Correspondence
Appointments · Promotions · Dismissals · Commendations · Queries · Condolences · Congratulations
→