Let's be honest for a second. You've finished writing your essay, run it through Microsoft Word or even a free version of Grammarly, and breathed a sigh of relief. No angry red squiggles. No major alerts. You think your grammar is clean.
And that's where you're being dangerously misled.
Those tools are designed to catch basic typos, the simplest of bugs. But they are completely blind to the "silent killers" in your writing—the errors that are grammatically "correct" but logically or contextually wrong. These are the subtle, insidious mistakes that make an IELTS examiner sigh and mark your score down from a 7.0 to a 6.5.
Think of your essay as a piece of code and the examiner as a strict, unforgiving compiler. As explained in our comprehensive guide to IELTS Band Descriptors, Grammatical Range and Accuracy (GRA) is one of the four critical pillars. A simple spelling mistake is a minor warning; it doesn't stop the program from running. But a subject-verb agreement error? That's a fatal error. It crashes your entire program—your final score.
In this guide, we're activating "debug mode." I will reveal the 10 most frequent fatal errors I've seen. We won't just identify them; we'll analyze why they crash your GRA (Grammatical Range and Accuracy) score and provide the exact "patch" to fix them for good.
The Debugging List: 10 Fatal Errors That Keep You at Band 6.5
Here is your bug report. Let's start debugging.
Subject-Verb Agreement Mismatch
The Bug:
The verb doesn't agree with its subject. This is the most common bug in the entire IELTS system, affecting both Task 1 data reports and Task 2 essays.
The Symptom:
The information provided by the charts show a clear trend.
Why It's a Fatal Error:
This is considered a fundamental, elementary error. To an examiner, it signals a lack of basic control over the English language, making a score of 7.0 or higher almost impossible.
The Patch:
❌ Before: The information provided by the charts show...
✅ After: The information provided by the charts shows... (information is singular)
Article Abuse (a/an/the)
The Bug:
Misusing or omitting definite and indefinite articles. This is the eternal pain point for most non-native speakers.
The Symptom:
Government should invest more money in the education.
Why It's a Fatal Error:
While a single article mistake isn't catastrophic, repeated errors create a sense of "unnaturalness" for the reader, indicating that the writer is not yet fluent.
The Patch:
❌ Before: ...invest more money in the education.
✅ After: ...invest more money in education. (education as a general concept does not need an article)
Comma Splices & Run-on Sentences
The Bug:
Incorrectly joining two independent clauses with just a comma, or with nothing at all.
The Symptom:
Technology has improved our lives, it makes communication easier.
Why It's a Fatal Error:
This demonstrates a weak understanding of sentence structure, a core component of the GRA score. It forces the examiner to mentally re-read and parse your sentences, which is a major red flag.
The Patch:
❌ Before: Technology has improved our lives, it makes communication easier.
✅ After (Option 1): Technology has improved our lives, as it makes communication easier. (Use a conjunction)
✅ After (Option 2): Technology has improved our lives. It makes communication easier. (Use a period)
Preposition Chaos (in/on/at/for)
The Bug:
Using the wrong preposition for a given context.
The Symptom:
The graph shows the data on 2025.
Why It's a Fatal Error:
Preposition errors, like article errors, create an "off" feeling. They are small but numerous, like a thousand tiny cuts that bleed your score away.
The Patch:
❌ Before: ...the data on 2025.
✅ After: ...the data in 2025.
Countable/Uncountable Noun Confusion
The Bug:
Treating uncountable nouns as countable.
The Symptom:
The government should provide more informations and advices.
Why It's a Fatal Error:
This is a classic non-native speaker error that is instantly recognizable to an examiner. It shows a gap in your fundamental vocabulary knowledge.
The Patch:
❌ Before: ...more informations and advices.
✅ After: ...more information and advice. (Or pieces of information/advice)
More Fatal Errors to Fix
#6Inconsistent Tense
The Bug: Randomly switching between past, present, and future tenses without a logical reason.
❌ When I was a child, I play outside every day. Now, I worked from home.
✅ When I was a child, I played outside every day. Now, I work from home.
#7Sentence Fragments
The Bug: Writing an incomplete sentence as if it were a complete one.
❌ For example, the increasing use of smartphones. (No main verb!)
✅ For example, we can see the increasing use of smartphones in our daily lives.
#8Dangling Modifiers
The Bug: A descriptive phrase doesn't clearly modify the correct noun.
❌ After finishing the essay, the pen was dropped. (The pen finished the essay?)
✅ After finishing the essay, I dropped the pen.
#9Incorrect Word Form
The Bug: Using the wrong form of a word, such as a noun instead of an adjective.
❌ The economy situation is getting worse.
✅ The economic situation is getting worse.
#10Faulty Parallelism
The Bug: When items in a list or comparison are not in the same grammatical form.
❌ I enjoy reading, writing, and to swim.
✅ I enjoy reading, writing, and swimming.
Watch: Common IELTS Grammar Mistakes Explained
Why You Can't Be Your Own Compiler: The Blind Spot Dilemma
Now, you might be thinking, "Great, I'll just keep these 10 mistakes in mind when I write." But here's the harsh truth: you can't.
There's a psychological phenomenon called "habitual blind spot." When you consistently make the same error, your brain learns to automatically "correct" it during proofreading. You literally become blind to your own most frequent mistakes. You can read your own essay a hundred times and still miss the subject-verb agreement error you've been making for ten years.
It's like a programmer trying to find all the bugs in their own code just by staring at it. It's impossible. You need an objective, tireless, automated testing tool that runs on pure logic, not on your biased human perception.
Conclusion: Stop Manual Debugging, Activate Your AI Compiler
IELTS grammar isn't magic. It's a system of rules. Your goal isn't to become a linguist; it's to produce clean, clear "code" that compiles successfully according to those rules.
You now know the 10 most common bugs. But what about the 11th, 12th, or 13th bug that is unique to your writing style?
Stop wasting your time with inefficient manual debugging through your own blind spots.
It's time to activate your personal "AI Compiler."
Key Takeaways: Your Grammar Debugging Checklist
10 Fatal Errors Identified
From subject-verb agreement to faulty parallelism—know the bugs that crash your score.
The Blind Spot Problem
Your brain automatically "corrects" your habitual errors when you proofread—you can't catch them alone.
Think Like a Compiler
Treat your essay as code and the examiner as a strict compiler checking for fatal errors.
AI Compiler Solution
Use automated AI analysis to get objective, comprehensive bug reports in seconds.
🎯 Self-Test: Can You Spot the Errors?
Below are 10 sentences, each containing ONE of the grammar mistakes we discussed. Can you identify and correct them?
"The number of students who studies abroad have increased dramatically."
💡 Show Answer
✅ Correct: "The number of students who study abroad has increased dramatically."
Error Type: Subject-Verb Agreement (Mistake #1)
Explanation: "who studies" → "who study" (plural students), and "The number...have" → "The number...has" (singular subject)
"Technology makes our life more convenient."
💡 Show Answer
✅ Correct: "Technology makes our lives more convenient."
Error Type: Countable/Uncountable Confusion (Mistake #2)
Explanation: "Life" as a countable noun referring to people's lives should be plural: "our lives"
"Despite technology has improved, people are less happy."
💡 Show Answer
✅ Correct: "Although technology has improved, people are less happy."
OR: "Despite the fact that technology has improved..."
Error Type: Despite vs. Although (Mistake #5)
Explanation: "Despite" takes a noun phrase, while "Although" takes a clause
"Government should provide the free healthcare to all citizens."
💡 Show Answer
✅ Correct: "The government should provide free healthcare to all citizens."
Error Type: Article Errors (Mistake #3)
Explanation: Need "the" before "government" (specific entity), but NO article before "free healthcare" (abstract concept)
"The data shows that pollution have increased."
💡 Show Answer
✅ Correct: "The data show that pollution has increased."
Error Type: Subject-Verb Agreement (Mistake #1)
Explanation: "Data" is plural → "show" (not shows), and "pollution" is singular → "has" (not have)