You've written a solid letter. The structure's there. The grammar's clean. But you lose 1.5 band points on "Appropriateness of Register" and wonder why.
Here's the reality: most IELTS candidates can't actually hear the difference between formal, semi-formal, and informal tone. So they can't write it either. This article teaches you to spot register mistakes before the examiner does, and shows you exactly what Band 7 tone sounds like in practice.
The IELTS band descriptors mention "appropriate register" for both Task 1 and Task 2. But they don't explain what that actually means. So you write something that sounds "polite enough" and hope it lands. It doesn't always work.
Here's what happens: examiners don't award points for good vibes. They mark against specific criteria. In Writing Task 1, your letter register must match the stated relationship between you and your reader. A complaint to a company manager demands formal tone. A note to a friend demands conversational tone. Get this wrong, and you drop from Band 7 to Band 6.5 or lower, even if everything else is perfect.
The tricky part? Tone lives in tiny details. A single word choice. A contraction. The way you open and close. These aren't dramatic grammar errors that scream "mistake." They're subtle. Invisible to untrained readers. But examiners spot them instantly.
IELTS Task 1 letters fit into three clear buckets: formal, semi-formal, and informal. You need to recognize which one fits your prompt, then stay inside that register without slipping.
Use formal register when you're writing to someone you don't know, in an official capacity, or about something serious. Think: company complaints, job inquiries, university applications, formal requests.
Formal tone markers:
Weak (Too Casual): "Hi there, I'm writing because your product is really bad. It broke after like two weeks and I'm pretty upset about it. Can you please fix this ASAP?"
Strong (Formal): "Dear Sir or Madam, I am writing to lodge a formal complaint regarding a product purchased from your company on 15th May 2026. The item ceased functioning after only two weeks of use, which falls well within the expected product lifespan. I would appreciate your prompt attention to this matter."
Semi-formal sits in the middle. You might know the person slightly, or the relationship is professional but not stiff. Think: emails to colleagues you've met before, requests to local council members you know by name, letters to a teacher who's friendly but still professional.
Semi-formal tone markers:
Weak (Too Formal): "Esteemed Municipal Official, I hereby submit my formal petition regarding the inadequate luminescence infrastructure in the residential vicinity."
Strong (Semi-Formal): "Dear Mr. Johnson, I hope this letter finds you well. I'm writing to request your assistance with a local issue that's affecting several residents on Elm Street. The street lighting has been inadequate for the past three months, and it's creating a safety concern."
Informal tone happens when you're writing to someone you know well: a friend, family member, peer, or someone you're on first-name terms with. It's forgiving, but it can still go wrong if you sound too careless or slang-heavy.
Informal tone markers:
Weak (Too Careless): "Yo Sarah! wassup?? I just wanted 2 tell u that ur party last week was lit lol. It was so fun innit. Let's do it again soon ya??"
Strong (Informal): "Hi Sarah, I hope you're doing well. I wanted to thank you again for organizing last week's party. It was such a fun evening, and I really appreciated seeing everyone there. Let's definitely do it again soon."
This is where most students slip up. You'll write a formal letter, then shift into casual language mid-way. Your opening is polished, but your closing tone changes. Or you start formal then suddenly use a contraction in paragraph two.
Examiners catch these shifts instantly. Even one sentence that breaks register can drop you from Band 7 to Band 6.5. Why? Because inconsistent register tells the examiner you don't actually control the language. You're guessing.
Real example: A student writes a formal complaint letter. First two paragraphs are perfect. Then: "Anyway, I really can't wait to hear back from you, so please hurry up and reply soon."
That one sentence breaks register. It's casual. It uses "can't" and "anyway" where formal demands "cannot" and a smoother transition. That one sentence costs you 0.5 band points.
Quick fix: Before you submit, read your letter aloud and mark every contraction, every casual phrase, every exclamation mark. If you find even three register breaks in a formal letter, rewrite those sentences. Your Band 7 score depends on consistency.
Your opening and closing carry enormous weight. They set and cement the tone. Get these two sections right, and you've already secured 70% of your register mark.
The words you pick either reinforce or sabotage your tone. Formal and informal vocabulary are completely different.
Formal vocabulary: request, inquire, ascertain, considerable, subsequently, endeavor, rectify, insufficient
Informal vocabulary: ask, find out, great, lots, then, try, fix, not enough
The key: don't mix them. A formal letter using "thanks" instead of "appreciation" sounds jarring. An informal letter using "endeavor" sounds pretentious and unnatural.
Weak (Mixed Vocabulary): "I am writing to inquire about the policy, and I'd be really grateful if you could hook me up with the details."
Strong (Consistent): "I am writing to inquire about your policy. I would be most grateful if you could provide me with further details regarding this matter."
Band 7 candidates don't just write letters. They think about audience first. They ask: "Who am I writing to? What's my relationship with them? What tone does that demand?" Then they pick a register and stick to it.
Here's their process:
You don't need to be a native speaker to do this. You just need to be intentional. Band 6 writers are careless. Band 7 writers are careful about tone from sentence one.
Your move: Before you start writing, write one sentence in your margin that locks in the register. "This letter to my boss about a meeting is semi-formal. No contractions. Polite but not stiff." Refer back to it after every paragraph.
Mistake 1: Formal letter with random contractions. A student writes a complaint to a company, and in paragraph two: "I've been a customer for five years." That "I've" breaks formal tone. Should be "I have been."
Mistake 2: Informal letter that's too stiff. A student writes to a friend: "I would be most grateful if you could attend my birthday celebration." That sounds like a formal invitation. Informal version: "I'd love it if you could come to my birthday party."
Mistake 3: Exclamation marks in formal letters. A formal complaint ending with "I look forward to your response!" sounds off. Formal tone demands a period. Save exclamation marks for informal letters.
Mistake 4: Slang in semi-formal. A letter to a councillor: "The roads here are totally messed up and we need cash to fix them ASAP." The words "messed up" and "cash" are too casual. Better: "The roads require urgent attention and adequate funding for repairs."
Mistake 5: Second person pronouns in formal. Don't write "you should fix this" in formal complaints. Write "this matter requires resolution" or "I would appreciate if this matter were addressed."
If you're still unsure about your letter structure overall, our guide on IELTS letter structure breaks down how to organize paragraphs correctly alongside proper tone.
Your first sentence does heavy lifting. It tells the examiner what register you're committing to. The wrong opening makes it nearly impossible to recover to Band 7, even if the rest is solid.
Formal opening (wrong): "Hi, I'm writing because I want to complain about something."
Formal opening (right): "Dear Sir or Madam, I am writing to lodge a formal complaint regarding..."
Informal opening (wrong): "I hope this letter finds you well, dear friend. I must inquire about the upcoming event."
Informal opening (right): "Hey Tom, hope you're doing well! I wanted to ask about your party next weekend."
The opening signals your register choice. Get it right immediately. The examiner is paying attention.
Contractions are the easiest way to break formal register. And examiners know it. They're literally looking for this.
In a formal letter: zero contractions. Not one. Not "it's" hidden in your third paragraph. Not "I'm" in your closing. Write out "it is", "I am", "do not", "cannot", "would not".
In semi-formal: use them sparingly. One or two is fine. More than that and you start sounding casual.
In informal: use them throughout. Your reader expects "I'm", "you're", "they're", "can't", "won't".
One contraction in a formal letter signals register inconsistency. That costs you points.
Reading your own work makes register shifts invisible. You hear what you meant, not what you wrote. Use this method instead: print your letter and read it aloud to someone who speaks English. Listen for moments where the tone sounds wrong or jarring. Mark them. Rewrite those sentences.
Our free IELTS writing checker flags register breaks automatically. It spots contractions in formal letters, inconsistent vocabulary, tone shifts between paragraphs, and mismatched openings and closings. You paste your letter and get instant feedback on register consistency alongside your predicted band score.
Writing in the right register takes practice, but you can speed it up with real feedback. Use an IELTS writing checker that evaluates letter tone and register specifically. It spots contractions in formal letters, slang in semi-formal letters, and tone shifts you might miss when reading your own work.
You write. It checks for register breaks, tone inconsistencies, vocabulary mismatches, and greeting/closing errors. You get a band score prediction instantly and see exactly which sentences or phrases break register.
If you're also working on your Task 2 essays, we have a guide on IELTS essay evaluation that covers how tone works in formal essay writing.
Get instant feedback on tone consistency, contractions, vocabulary matching, and register shifts. See your likely band score in seconds.
Check My Letter FreeYour closing paragraph needs to match your opening register perfectly. If you opened formally, close formally. Many students nail the opening, then slip in the closing.
Formal closing: "I look forward to receiving your response at your earliest convenience. Yours sincerely, [Your name]"
Semi-formal closing: "I would appreciate your help with this. Thank you for your time. Best regards, [Your name]"
Informal closing: "Let me know what you think. Cheers, [Your name]"
The closing is your last chance to reinforce register consistency. Make it count.