Here's what happens in most IELTS Writing Task 1 letters: students pick a tone and stick with it. Problem is, they pick the wrong one.
You're asked to write a complaint letter to your landlord, and you write "Hey mate, fix the leak ASAP or I'm out." That's friendly. But it's also a Band 5 response. Or you write to a friend requesting help, and you sound like you're submitting a legal document. That's formal. But it's also awkward and nobody talks like that.
The examiners aren't grading you on politeness. They're grading you on register accuracy. That means matching your tone, vocabulary, and grammar to the relationship described in the task. Get it right, and you unlock points across Task Response, Coherence & Cohesion, and Lexical Resource. Get it wrong, and you lose marks even if your spelling is flawless.
This guide teaches you exactly how to spot the right tone before you write a single sentence, and how to check your letter once it's done using a structured tone verification system.
Here's the reality: the IELTS band descriptors explicitly reward "appropriate register." Look at the official Band 7 descriptor—examiners are specifically looking for "appropriate register" and "effective use of vocabulary." Drop to Band 5, and they're already marking you down if your tone doesn't fit the context.
Most students treat Task 1 letters as a binary choice: robotic or sloppy. But that's not how real English works.
The task prompt tells you who you're writing to. Read it carefully. That single phrase determines everything about how you write the next 150 words.
Formal letters are the backbone of IELTS Task 1. You'll write to companies, councils, schools, or government bodies. These are strangers or distant contacts.
Formal tone has specific markers. Look for these patterns in your own writing:
Weak: "I'm really annoyed about the noise from next door. Can you guys do something about it? I've been losing sleep for weeks now."
Good: "I am writing to lodge a formal complaint regarding persistent noise disturbances from the adjacent property. The situation has significantly disrupted my sleep patterns over the past several weeks."
See the difference? The weak version uses contractions, casual phrasing ("guys"), and choppy sentences. The good version avoids contractions, uses stronger vocabulary ("lodge a formal complaint", "disrupted"), and builds longer sentences with dependent clauses.
But here's where students mess up: formal doesn't mean pompous. Don't write like you're drafting a legal will. You're still a person writing to another person. Keep your vocabulary accessible. Use "help" instead of "assistance" if help is natural in context. Formal means professional clarity, not thesaurus abuse.
Informal letters go to people you know. A friend, a family member, someone you have a casual relationship with. You're still writing English, but you sound like yourself.
Informal tone has its own markers:
Weak: "I hope this letter finds you in good health. I am writing to request your assistance with a matter of significant importance."
Good: "I'm writing because I need your help with something. I know you've been through this before, and I thought you might have some advice for me."
The weak version sounds robotic even for a friend. Too much formality kills the warmth. The good version is direct, personal, and warm. It acknowledges the relationship and asks naturally.
The key here? Don't try to sound fancy when you're being casual. You'll sound fake. Examiners can tell. Instead, write like you're actually talking to that person, but on paper.
Some Task 1 prompts sit in the middle. You might be writing to a work colleague you don't know well, or a neighbor, or someone you've just met. These are semi-formal situations.
In semi-formal letters, you can:
Good semi-formal: "Dear Ms. Rodriguez, I'm writing to ask about the project timeline we discussed. I've reviewed the initial proposal and have a few questions about the implementation phase. I'd appreciate your thoughts on this matter."
This hits the middle ground. There's a contraction ("I'm", "I'd"), but the overall tone stays professional. The vocabulary is clear but not stiff. The opening uses a title, then softens slightly while staying respectful.
You've written your letter. Now you need to check it. Here's a system that actually works.
Step 1: Highlight all contractions. Count them. If it's a formal letter and you have more than one or two, rewrite some sentences without contractions. If it's informal and you have none, add a few. Real informal writing has contractions.
Step 2: Look at your sentence openers. Underline the first word of every sentence. Formal writing varies them: "I am concerned...", "The issue is...", "This situation...". Informal writing is simpler and more repetitive: "I've...", "You know...", "I need...", "Can you...". Does yours match the task?
Step 3: Check your requests or complaints. How do you ask for things? Formal: "I would appreciate it if you could..." Informal: "Can you...?" or "Would you mind...?" Find every request and mark its tone. They should all be consistent with your overall register.
Step 4: Read the closing aloud. Does it sound right for your relationship? "Yours faithfully" for formal to a stranger. "Cheers" for informal to a friend. If it feels off, change it.
Step 5: Reread the task prompt. Who are you writing to? Are they a friend, a family member, a company, a school? That single detail should drive every tone choice you made. If it doesn't, revise.
Pro tip: Print out your letter and read it aloud. Your ear catches tone issues your eyes miss. If you stumble over a sentence or it sounds awkward, that's probably the wrong register for that part.
Example 1: Formal Complaint
Prompt: "You have bought a piece of furniture from a large furniture store. However, when it was delivered, the furniture was damaged. Write a letter to the manager of the store and describe the problem. Ask what action the store will take."
Who are you writing to? A manager you don't know. Register? Formal. What does that mean for this letter?
Good opening: "Dear Sir or Madam, I am writing to lodge a complaint regarding a sofa I purchased from your store last week. Upon delivery, I discovered significant damage to the right arm of the chair, which makes it unsuitable for use."
Notice: full salutation, "I am" (not "I'm"), complete sentences, specific details about the problem. No slang. No friendliness that would be out of place with a stranger. If you want more detail on getting the letter format right, that's worth checking too.
Example 2: Informal Catch-Up
Prompt: "An old school friend recently contacted you. Write a letter to your friend. In your letter, tell them what you've been doing since you last met and ask about their life and plans."
Who are you writing to? A friend. Register? Informal. What does that mean?
Good opening: "Hi Sarah, It was great to hear from you after so long! I've been meaning to get in touch myself. So much has changed since we last saw each other."
Notice: first name, contractions ("It was", "I've"), shorter sentences, warmth. You're writing like you actually talk to this person. There's personality here without breaking any rules.
Over-formality in informal letters. This is the most common error. Students think formal equals good, so they formalize everything. But writing to a friend in ultra-formal English sounds fake and distant. Examiners mark you down for register mismatch, not for being too friendly.
Under-formality in formal letters. The opposite problem. You're writing to a company or official body, but you sound like you're texting a mate. "Fix the problem ASAP" to a hotel manager won't get you a refund. It'll get you a Band 5 for register.
Mixing registers within the same letter. You open formal, then drift casual, then return to formal. This inconsistency confuses examiners and costs coherence marks. Pick your register and commit to it.
Misreading the relationship. The prompt says "an old family friend." You write formal. But the tone should be warm and familiar, not stiff. The relationship matters more than whether you're making a request. Read the prompt twice if you need to.
Quick fix: Write the salutation and closing first. They anchor your register. If you open with "Dear Mr. Chen" and close with "Yours sincerely", you've committed to formal. Don't break that promise in the middle with slang.
On your next practice letter, apply this test. Before you submit or check it, use the five-step system above. Then read it one more time asking: does this sound like how I'd actually speak to this person? If the answer is "no", your register is probably off.
Once you've self-checked, use an IELTS writing checker to see if examiners agree with your tone assessment. The feedback will show you exactly where tone issues hit hardest: Task Response (are you being appropriate to the context?), Coherence & Cohesion (does the tone stay consistent?), and Lexical Resource (are your word choices register-appropriate?).
Band 7 letters don't just sound good. They sound right. That's the difference between guessing and knowing.
Register isn't just about contractions and politeness. It shows up in your grammar choices too.
In formal letters, you'll see passive structures more often: "It has been arranged that..." instead of "I've arranged..." You'll see complex sentence structures with subordinate clauses. You'll use modal verbs cautiously: "would you be able to" instead of "can you."
In informal letters, you'll use active voice almost always. "I've done this" not "This has been done by me." You'll use simpler sentence structures. You'll ask directly: "Can you help?" not "Would you be willing to consider assisting?"
Vocabulary matters just as much. A formal letter uses words like "regarding," "subsequently," "endeavor," "ascertain." An informal letter uses everyday words: "about," "then," "try," "find out." If you're writing to a friend but using words you'd find in a legal document, you're signaling the wrong register.
When you're checking your letter with an IELTS writing checker, look specifically at the grammar and vocabulary choices. Are they consistent with the relationship? That consistency is what pushes you from Band 6 to Band 7.
Your opening and closing are the biggest register signals. They telegraph your entire tone in 10 words.
Formal openings: "Dear Sir or Madam," "I am writing to..." or "I write to..." Informal openings: "Hi Sarah," "How are you?" "It was great to hear from you."
Formal closings: "Yours faithfully" (when you don't know the name), "Yours sincerely" (when you do), "Kind regards." Informal closings: "Cheers," "Take care," "Best," "All the best," "Looking forward to hearing from you."
Many students get the opening right but mess up the closing. You write a formal letter, then sign off with "Cheers." That mismatch costs marks. If you want to dive deeper into letter closings, that guide covers what examiners look for in your sign-off.
Appropriate register means your tone, word choice, and grammar match the reader and context. A formal complaint letter should sound professional and respectful. An informal letter to a friend should sound warm and conversational. Examiners check for register accuracy as part of Task Response scoring.
When you're unsure, ask yourself: "Would a native English speaker actually talk this way to this person?" If yes, your register is probably right. If no, adjust.
Get instant band score feedback and line-by-line analysis of your letter's tone, vocabulary, and grammar. Know exactly where your register works and where it needs adjustment.
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