Some messages are too important for a casual email: ending a contract, asking for money that is overdue, giving someone permission to act for you, complaining about a serious fault. For these, a formal business letter does three things. It states the facts so nobody can claim they misunderstood. It asks for one clear thing. And it leaves a record.
Formal does not mean cold or old fashioned. The best formal letters are plain, short and calm. They are written so that a stranger, such as a manager, a judge or an auditor, could read them in a year and understand exactly what happened and what was asked.
Know your one purpose
Before you write, finish this sentence: "After reading this letter, the reader should ___." Pay the invoice. Confirm the cancellation. Replace the faulty item. Accept that Maria can sign on my behalf. If you have two purposes, you probably need two letters.
Then decide what you will do if the reader does not respond, because the letter should say it.
The structure that works
- Your details and the date. Name, address, contact information, and the date written.
- Their details. The person or department, the company and the address. Use a name if you can find one.
- A reference line. A subject that identifies the matter: "Invoice 2041 dated 3 March, unpaid" or "Termination of subscription, account 77812".
- The opening. Say why you are writing in the first sentence.
- The facts. What happened, in order, with dates, numbers and documents.
- What you want. One clear request, with a date.
- What happens next. The step you will take if there is no reply, and how to reach you.
- A courteous close and your signature.
Keep it to one page where you can. Attach copies of documents, never originals, and list them at the bottom.
Be exact about facts
Strong letters are made of specifics:
- Dates: the day the service was ordered, delivered, due and not paid.
- Amounts: the figures, the currency and what they cover.
- References: invoice, order, contract and account numbers.
- Earlier contact: "I called on 12 March and spoke to Ahmed, who promised to call back. I wrote on 19 March. I have not had a reply."
Leave out opinions and speculation about motives. "You have ignored us" is an opinion; "I wrote on 19 March and have had no reply" is a fact that makes the same point.
Ask for one thing, with a date
"Please pay the 1,250 owed by invoice 2041 by 28 March." "Please confirm in writing by 15 April that the contract ends on 30 April." Vague wishes get vague answers. Choose a deadline that is fair, usually seven to fourteen days, and say what you will do afterwards.
Keep the tone steady
Firm and polite is a strong position. Avoid sarcasm, capital letters and threats you will not carry out. Do not accuse; describe. If you are angry, write the angry version, put it aside and rewrite it the next day.
If you are the one in the wrong, say so briefly and move to the solution. Our post on payment reminder emails shows the gentler first steps before a formal letter is needed.

