Here's the thing: most IELTS students lose marks on Task 1 letters not because they can't write, but because they get the tone wrong. You could have perfect grammar and hit the word count, but if you write a formal letter to a friend or an informal letter to a company, you've already damaged your band score. The IELTS band descriptors reward "appropriate register" explicitly, meaning examiners are looking specifically for whether you match your tone to your audience. This guide shows you exactly how to spot tone mistakes and fix them before you submit.
Task 1 letters account for 33% of your writing score. That's one-third of your entire writing band. The IELTS criteria for Task Response specifically mentions "appropriate register for an informal/formal letter," so the examiner is literally checking if you've nailed the tone before they even look at your vocabulary.
Here's what happens in real marking: An examiner sees you've written 160 words, your grammar is clean, your ideas are clear. But you've addressed a company complaint with "Hey mate, I'm really annoyed about this" instead of "I am writing to express my concern regarding..." Your lexical resource takes a hit. Your task response takes a hit. You drop from band 7 to band 6 on that criterion alone.
The good news? Tone is fixable. Unlike grammar, which takes weeks to improve, you can learn to switch register in days.
Let me be blunt: formal and informal aren't just about politeness. They're about distance and relationship.
This difference shows up in every single sentence. Not just big words. Small words matter too.
Before you submit any Task 1 letter, run through this checklist. It takes 90 seconds and catches most register mistakes.
Too informal for formal: "Hi there, I'm writing because I had a bad experience at your hotel."
Better: "Dear Sir/Madam, I am writing to lodge a complaint regarding my recent stay at your hotel."
In formal letters, you use "Dear Sir/Madam" (if you don't know the name) or "Dear [Name]." You announce your purpose: "I am writing to..." or "I am writing because..." In informal letters, you use "Hi," "Hello," or just jump in with "How are you?"
This is where students slip up constantly. Formal writing avoids contractions. Period.
Too informal: "I'm disappointed and I've tried to contact you, but you haven't responded."
Better: "I am disappointed and I have tried to contact you, but you have not responded."
In formal letters, write "I am," "I have," "you have not." In informal letters, contractions are exactly what you want: "I'm really excited," "I've been meaning to ask you," "you haven't visited in ages."
Formal language uses more sophisticated, neutral words. Informal language uses everyday words and emotional punch.
Too casual: "The food was really bad and the service was awful. I was super upset."
Better: "The food was of poor quality and the service was unsatisfactory. I was extremely disappointed."
Notice: "bad" becomes "poor quality," "awful" becomes "unsatisfactory," "super upset" becomes "extremely disappointed." The meaning stays the same, but the tone shifts. In formal letters specifically, swap these words: problem becomes issue, ask becomes inquire, help becomes facilitate, fix becomes rectify.
Wrong for formal: "Cheers, Sarah"
Right for formal: "Yours faithfully, Sarah" (when you used "Dear Sir/Madam") or "Yours sincerely, Sarah" (when you used "Dear Mr. Jones")
Formal letters close with "Yours faithfully" or "Yours sincerely." Informal letters close with "Best wishes," "Warm regards," "All the best," or just "Thanks." Never use "Cheers," "Talk soon," or "Take care" in formal Task 1 letters.
Formal writing builds longer, more complex sentences. Informal writing punches with short ones.
Too simple: "I stayed at your hotel. It was bad. I want a refund."
Better: "During my stay at your establishment, I experienced several issues that fell below your advertised standards, and I would therefore appreciate either a substantial refund or compensation for the inconvenience caused."
See the difference? Formal letters use subordinate clauses, passive constructions, and longer noun phrases. You're building professional authority through sentence weight.
These are the patterns examiners see constantly, and they all lower your band score.
You start formal ("Dear Sir/Madam, I am writing to inquire...") but then drift informal ("...and it's really annoying because the staff were super rude"). This inconsistency shows weak control of register and directly impacts the Coherence and Cohesion criterion.
Words like "got," "gonna," "basically," "like," "stuff," and "thing" don't belong in formal Task 1. Neither do phrases like "FYI," "ASAP," or "no worries." Replace them with: received, will, essentially, such as, matter, and certainly or understood.
If the letter topic is a complaint, broken service, or request for help, you must sound professional. Writing "Your WiFi is absolutely rubbish" to a hotel shows poor judgment. Use "The WiFi was unreliable" instead. The examiner is assessing whether you understand social norms.
If the prompt gives you a name for a formal letter (example: write to "Mrs. Helen Crawford, Manager"), use her title and surname. "Dear Mrs. Crawford" is formal. "Dear Helen" is not, even if you know her. The prompt structure tells you which register to use.
Use this method every single time you write a Task 1 letter. It takes 3 minutes and catches tone mistakes before they hurt your score.
Step 1: Identify the audience and relationship. Read the prompt carefully. Are you writing to someone you know (a friend, relative, colleague you're close to) or someone you don't know (a company, official, stranger)? Write this down. It's your anchor.
Step 2: Scan for register markers. Go through your letter and underline every contraction, every casual word, every short blunt sentence. Compare that list to your audience. If you're writing to a stranger and you've underlined 5+ items, you're too informal. If you're writing to a friend and you sound like a lawyer, you're too formal.
Step 3: Check the opening and closing. These are the easiest places to verify tone because they're formulaic. If your opening matches the audience (formal opening for unfamiliar person, informal opening for friend) and your closing is appropriate, your register is probably solid elsewhere too.
Pro tip: Print your letter and read it aloud. Your ear catches tone mistakes faster than your eyes. If you cringe at any sentence because it sounds "off," that's usually a register problem. You can also use an IELTS writing checker to catch these inconsistencies instantly.
Let's look at two actual Task 1 prompts and show how tone changes the response.
Prompt 1: "You have just completed a course at a language school. Write a letter to the school administrator requesting a reference letter for a job application."
This is formal. You don't know the administrator personally. The relationship is professional.
Too informal: "Hey, I just finished your English course and it was great. Could you write me a reference letter? I need it for a job I'm applying for. Thanks heaps!"
Better: "Dear Sir/Madam, I have recently completed the Advanced English course at your institution and would be most grateful if you could provide a reference letter to support my application for a teaching position. The position requires evidence of language proficiency, which I believe your course has provided me. I would be happy to provide any additional information you require."
Prompt 2: "You have been staying with a friend and are about to leave. Write a letter thanking them for their hospitality."
This is informal. You know the person well. The relationship is personal.
Too formal: "Dear Friend, I am writing to express my gratitude for the hospitality you have extended during my recent residence in your domicile. I would like to formally acknowledge your kindness."
Better: "Hi Sarah, I can't thank you enough for putting me up these past two weeks. You've been amazing, and I really appreciate how you made me feel at home. The dinners, the chats, everything was brilliant. I'll definitely be back soon, and next time it's on me!"
Same person could write both, but the tone completely shifts based on audience. That's what examiners are looking for.
The IELTS Analytical Descriptors don't give you points for tone directly, but poor register lowers you across multiple criteria. Here's how it works in real marking.
Task Response (25% of your writing score): If your tone doesn't match the task, examiners view you as not fully understanding the prompt. This drops your Task Response score, sometimes by half a band.
Lexical Resource (25% of your score): Using casual language when formal is required signals weak vocabulary range. You're not showing you can "select vocabulary precisely" (the Band 8 descriptor). You might score a 6.5 instead of 7.5 on this criterion.
Grammatical Range and Accuracy (25% of your score): Contractions in formal writing, informal sentences in professional contexts, these are seen as grammatical errors in register. You lose accuracy points.
Real example: A student writes a formal complaint letter but uses "I'm really upset," "the room was gross," and "Thanks." The examiner might score her Task Response 7 (didn't fully meet formal register), Lexical Resource 6 (casual vocabulary, imprecise choices), Grammatical Range 6.5 (register errors). That's a 6.5 overall, when she might have scored 7.5 if tone had been correct.
Getting tone right is worth nearly a full band. It's one of the fastest wins in IELTS writing.
Most Task 1 prompts are clear: formal or informal. But occasionally you'll hit a prompt that feels ambiguous. Here's how to handle it.
Writing to someone you know professionally. You're friends with your manager outside work, but the letter is about work. Use formal. The context (business-related) overrides the relationship. Err on the side of respect.
Writing to a peer in an organisation. "Write to a colleague about a project delay." If the prompt says "colleague" with no hint you're close, use semi-formal. Open with "Dear [Name]" and use "I am" instead of "I'm," but you can be slightly warmer than you would be with a stranger.
Unsure about the name format. If the prompt doesn't specify a name, use "Dear Sir/Madam" for formal. If it does give a name, use it. Don't overthink this.
Read the prompt and note the relationship. If you know the person, use informal tone with contractions, casual vocabulary, and a warm closing. If you don't know them or the context is professional, use formal tone: full words, sophisticated vocabulary, and a professional closing. This single distinction determines 80% of your register choices.
Use our free IELTS writing checker to verify your letter tone and register before you submit. Get instant feedback on formality, vocabulary, and grammar across all your Task 1 letters.
Check My Letter NowPin this mental checklist to your desk when working on formal vs informal letter writing.
| Formal Register | Informal Register |
|---|---|
| Dear Sir/Madam or Dear [Name] | Hi [Name] or Hello |
| I am, I have, you are | I'm, I've, you're |
| Issue, inquire, facilitate, rectify | Problem, ask, help, fix |
| Long, complex sentences | Short, punchy sentences |
| Yours faithfully / Yours sincerely | Best wishes, All the best, Thanks |
Bookmark this table and reference it before you write. After a few letters, the markers will stick and become automatic.
Knowing tone markers isn't the same as using them automatically. Here's what actually works.
Write one formal and one informal letter this week. Spend 20 minutes on each. Don't worry about hitting the word count yet. Just focus on tone. Check your letter against the five elements in the checklist. Count your contractions. Underline your casual words. Do this twice, and you'll never mix register again.
If you want faster feedback, try our IELTS writing checker which highlights register inconsistencies in real time. You learn while writing instead of after you've finished. Most students who use tools for IELTS writing correction improve their register accuracy within one week.
The students who improve fastest are the ones who treat tone as a mechanical skill first, not an intuition. Follow the rules for two weeks. Then it becomes automatic. You'll recognize when a sentence sounds too casual or too stiff before you even finish typing it.