You've written 160 words. Your grammar looks solid. Your tone feels formal. And then your examiner gives you a Band 6 instead of the Band 7 you expected.
What probably happened is this: your letter did everything right except the one thing that actually matters. It didn't answer what the task asked you to do.
This is where most students slip up. They master the mechanics of letter writing but completely miss the purpose. The IELTS band descriptors use "Task Response" to score this skill, and it counts for 25% of your score. That's a quarter of your band score. You can't afford to let this slide.
Here's what a purpose mismatch looks like, why it tanks your score, and how to catch it before your examiner does using a simple IELTS writing checker system you can build yourself.
A purpose mismatch happens when your letter checks all the formal boxes but fails to do what the prompt actually asks. You've written a polite, well-structured letter to the wrong person about the wrong problem.
Look at what the IELTS descriptors actually say. At Band 7, it states: "The response addresses all parts of the task, though some parts may be more fully covered than others." At Band 6, it says: "The response addresses the task, though some parts may not be fully covered."
That sounds like a small difference on paper. In reality, it's massive. A Band 6 letter might touch on what you're asked to do without fully committing to it. A Band 7 letter tackles every single element of the prompt head-on.
Weak (Band 6): You're asked to write to a hotel manager about a poor experience and request compensation. Your letter apologizes politely, describes the issues, but ends with "I hope you will consider my request" without actually stating what compensation you want. You've touched the purpose but haven't fully addressed it.
Good (Band 7): Same scenario. Your letter describes the problems, explains the impact (you had to spend extra on alternative accommodation), and clearly requests either a partial refund or a discount on your next stay. You've addressed every part of the task.
The difference isn't about sounding clever. It's about completeness.
Type 1: Missing one part of the task entirely. The prompt asks you to complain and suggest a solution. You only complain. Or you suggest solutions without actually stating what's wrong.
Type 2: Addressing the wrong audience or context. The prompt asks you to write to a council about noise pollution. You write as if you're texting a friend or emailing a newspaper. The tone is off, which means the purpose is off.
Type 3: Not giving enough detail on key points. The prompt asks you to explain your reasons for moving. You mention "a new job" but don't explain why this job matters, what it means for your future, or how it connects to your current situation. You've acknowledged the prompt without actually exploring it.
Quick tip: Read the prompt three times before writing. Underline every single thing it asks you to do. If you can't list the tasks as separate bullet points, you don't understand the prompt clearly enough yet.
You don't need software to catch these. You need a system. Here's the one that works and takes just 3-4 minutes per letter.
This simple system catches 90% of purpose mismatches that would otherwise drop you from Band 7 to Band 6.
Let's walk through an actual IELTS-style prompt and show you a weak version next to a strong one.
Prompt: "You have recently moved to a new city for work. Write a letter to your friend back home. Explain why you moved, describe what you like about the city, and ask about their plans to visit you."
Three tasks: explain the move, describe the city positively, ask about their visit.
Weak (Purpose Mismatch): "Dear Sarah, I hope you are well. I have moved to London because I got a new job. The city is large and has many people. I am happy here. When will you visit me? I look forward to hearing from you. Best wishes, Alex."
What's missing? The letter mentions all three tasks but doesn't develop any of them. "I got a new job" doesn't explain why this move mattered or what you'll gain. "The city is large and has many people" doesn't show what you actually like about it. "When will you visit me?" doesn't express genuine interest or give reasons why you want them there. It reads like a checklist, not a letter.
Good (Purpose Fulfilled): "Dear Sarah, I hope you've been well. I'm writing to tell you about my move to London. I accepted a position with a tech company here, and after three years in the same role back home, I really needed a fresh challenge and a chance to build my career in a bigger market. The city has exceeded my expectations. There's an incredible food scene (you'd love the Vietnamese restaurants in Hackney), and I'm living near the Thames, so I can run along the river every morning. We always talked about doing that together. I'd love for you to visit soon, especially in autumn when the city is less crowded. We could catch up properly, and I could show you around. Do you think you might take a week off in September or October? Looking forward to hearing from you. Best, Alex."
What works? The letter explains the move with real detail (specific company, why it mattered). It describes the city with concrete examples (the food scene, the Thames, the running route). It asks about the visit with a specific invitation (September or October), not just a generic question. This fulfills the purpose completely and would score Band 7 for task response.
The second letter isn't drastically longer. It's just more detailed and more committed to what it's saying.
The IELTS exam measures whether you can communicate for real purposes. Task 1 isn't about showing off fancy grammar or vocabulary. It's about writing something that actually works.
If you send a job application that mentions the company's great benefits but never explains why you're a good fit, you won't get hired. Your letter failed its purpose. Examiners think the same way. A letter that partially addresses the prompt is a letter that wouldn't achieve its goal in real life.
At Band 7, examiners expect you to handle every element of the task. At Band 6, they accept that you might miss some depth. That difference costs you roughly 25-30% of your Writing score, which can drop you from a 7.0 to a 6.5 overall.
Quick tip: The IELTS Writing Task 1 is marked out of 9. Task Response is one of four criteria, each weighted equally. If you score a 6 for Task Response but a 7 for everything else, your overall band is a 6.5, not a 7. Don't let purpose mismatches drag you down.
Here's what happens constantly: students nail the formal letter tone but use the wrong tone for the actual purpose.
A formal tone doesn't mean cold and robotic. It means appropriate formality. If you're writing to a council about a local problem, you should be respectful but direct. If you're writing to an old colleague you haven't spoken to in years, you should be warm but professional. The tone has to match the purpose and the relationship. For more on getting this balance right, our guide to letter tone authenticity and formality breaks down exactly how examiners evaluate this.
Weak (Tone Mismatch): Prompt asks you to write to an old university friend inviting them to your birthday party. You write: "Dear Mr. Johnson, I am writing to formally notify you of an upcoming social gathering. Your attendance would be appreciated. The event will take place on the 15th of June at 7:00 PM. Kindly confirm your availability at your earliest convenience. Yours faithfully, Alex."
The tone is too formal for the purpose. You're writing to a friend, not a bank manager. This reads cold and wrong, even though the grammar is technically perfect.
Good (Tone Matches Purpose): "Dear Tom, I hope you're doing well. I'm throwing a birthday party on the 15th of June at 7:00 PM and would love for you to come. It's been ages since we caught up, and it would be great to see you there. Do let me know if you can make it. Hope to see you then. Best, Alex."
This is still a proper letter, but the tone fits the relationship and purpose. It's warm without being sloppy, clear without being stiff.
The second version fulfills its purpose better because it sounds like a real person writing to a real friend, not a machine checking boxes.
Before you submit any Task 1 letter, go through this checklist. If you answer "no" to any question, fix it.
This checklist is more useful than any template. Templates trick you into thinking structure equals purpose. It doesn't.
A Band 7 letter must address every part of the prompt with specific detail and appropriate tone. This means each task element gets developed with concrete examples or clear reasoning, not just mentioned. The letter should sound natural for its intended recipient and context.
Most Band 7 Task 1 letters run 160-180 words (well above the 150-word minimum) because they develop ideas fully rather than just ticking boxes. They show the writer understood what the prompt asked and delivered exactly that.
Purpose mismatch is one of the most fixable errors in Task 1 letter writing. It's not about grammar. It's not about vocabulary. It's about paying attention to what the prompt asks and actually delivering it.
The difference between a Band 6 and Band 7 letter is often just a few minutes of careful checking. Use the checklist above before you submit. Read the prompt three times. Make sure every element is covered. Make sure your tone matches your audience. Do that, and you'll catch mismatches that would have cost you half a band.
Want to test your understanding? Try writing a practice letter using the system described here, then use our free IELTS writing checker to see if you've covered all parts of the task.
Our IELTS writing checker analyzes your Task 1 letters for purpose mismatches, tone consistency, and task coverage. Get instant feedback on exactly what to fix.
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