IELTS Grammar: The 5 Errors That Cost You the Most Marks

Reading time: 14 minutes

Grammar accounts for 25% of your IELTS Writing score. That's the same weight as Task Response, Coherence, and Vocabulary - yet many students focus on the other three while hoping their grammar is "good enough."

Here's what the band descriptors tell us:

Band 6: "Uses a mix of simple and complex sentence forms. Makes some errors in grammar and punctuation but they rarely reduce communication."

Band 7: "Uses a variety of complex structures. Produces frequent error-free sentences. Has good control of grammar and punctuation but may make a few errors."

The difference between Band 6 and 7 comes down to error frequency and sentence variety. You don't need perfect grammar - you need to minimise the errors that hurt your score most.

This guide identifies the five most damaging grammar mistakes and gives you practical strategies to eliminate them.

Error 1: Subject-Verb Agreement

This is the most common grammatical error in IELTS essays, and it directly affects your score because examiners can't ignore it.

The Problem

The subject and verb must agree in number (singular/plural):

• Singular subject - singular verb
• Plural subject - plural verb

Sounds simple, but in practice:

• Wrong: "The government need to take action."

• Correct: "The government needs to take action."

• Wrong: "The advantages of this approach is clear."

• Correct: "The advantages of this approach are clear."

Why It Happens

Complex subjects confuse writers:

In "The advantages of this approach is clear," the word closest to the verb is "approach" (singular), but the actual subject is "advantages" (plural).

Collective nouns vary:

"Government," "company," and "team" are grammatically singular in British English:

• "The government is planning..."

But the plural meaning tricks many writers.

How to Fix It

Strategy 1: Identify the true subject

Cross out prepositional phrases to find the subject:

"The impact [of rising temperatures] is significant."
"The benefits [of this policy] are numerous."

Strategy 2: Check every "is/are" and "has/have"

Before submitting, specifically look for these verbs and verify agreement:

• Singular subjects: is, has, was, does
• Plural subjects: are, have, were, do

Strategy 3: Memorise tricky cases

Error 2: Run-On Sentences and Comma Splices

These errors directly affect both Grammar and Coherence scores.

The Problem

Run-on sentence: Two complete sentences joined without punctuation.

• Wrong: "Technology has many benefits it also has drawbacks."

Comma splice: Two complete sentences joined only by a comma.

• Wrong: "Technology has many benefits, it also has drawbacks."

Why It Matters

These errors:

• Make your writing hard to follow
• Suggest you don't understand sentence boundaries
• Can completely change your meaning

How to Fix It

Option 1: Use a period

• Correct: "Technology has many benefits. It also has drawbacks."

Option 2: Use a semicolon

• Correct: "Technology has many benefits; it also has drawbacks."

Option 3: Add a conjunction

• Correct: "Technology has many benefits, but it also has drawbacks."

Option 4: Use a subordinating conjunction

• Correct: "Although technology has many benefits, it also has drawbacks."

The Comma Rule

A comma alone cannot join two complete sentences. You need:

• Comma + conjunction (and, but, so, yet, or)
• Semicolon
• Period

Test: Can each part stand alone as a complete sentence? If yes, you need more than a comma.

Error 3: Article Errors

Article mistakes are incredibly common and can appear multiple times per sentence, significantly affecting your error count.

The Problem

Missing articles:

• Wrong: "Government should invest in education."
• Correct: "The government should invest in education."

Unnecessary articles:

• Wrong: "The happiness is important."
• Correct: "Happiness is important."

Wrong article choice:

• Wrong: "This is a important issue."
• Correct: "This is an important issue."

Quick Article Rules

Use "the" when:

• Referring to something specific: "the government," "the environment"
• Using superlatives: "the most important," "the best"
• Something is unique in context: "the internet," "the main reason"
• The noun has been mentioned before

Use "a/an" when:

• Introducing something for the first time
• Referring to any member of a category: "a student," "an essay"
• Before countable singular nouns in general statements

Use no article when:

• Making general statements with plural nouns: "Children need education."
• Discussing abstract concepts: "Happiness is valuable."
• Talking about things in general: "Technology has changed society."

Practice Focus

Most article errors involve:

1. Missing "the" before specific references
2. Adding "the" to general concepts
3. Missing "a/an" before singular countable nouns

Create a mental checklist for these three patterns.

Error 4: Incorrect Verb Tenses

Tense inconsistency confuses readers and signals weak grammatical control.

The Problem

Mixing tenses without reason:

• Wrong: "The study was conducted in 2020. It shows that students prefer online learning."
• Correct: "The study was conducted in 2020. It showed that students preferred online learning."

Wrong tense for context:

• Wrong: "In the past, people travel by horse."
• Correct: "In the past, people travelled by horse."

IELTS Tense Guidelines

Present Simple (for general truths and current situations):

• "Technology plays an important role in education."
• "Many countries face environmental challenges."

Present Perfect (for changes over time, recent developments):

• "Technology has transformed the way we communicate."
• "Studies have shown that exercise improves mental health."

Past Simple (for completed actions, historical examples):

• "A 2019 study found that..."
• "In the 20th century, most people worked in agriculture."

Future/Conditionals (for predictions and possibilities):

• "If governments invest in education, literacy rates will improve."
• "This could lead to significant improvements."

Staying Consistent

Choose a primary tense for each paragraph and stick with it:

• Paragraph discussing current situation - present tense dominant
• Paragraph discussing historical example - past tense dominant
• Paragraph making predictions - future/conditional dominant

Error 5: Sentence Fragments

Fragments are incomplete sentences that lack a subject, verb, or complete thought.

The Problem

• Wrong: "Although many people use social media. They often feel lonely."

• Correct: "Although many people use social media, they often feel lonely."

• Wrong: "Such as cars, trains, and buses."

• Correct: "Various modes of transport are available, such as cars, trains, and buses."

• Wrong: "Because technology has many advantages."

• Correct: "This is important because technology has many advantages."

Why Fragments Happen

Subordinate clauses standing alone:
"Although...", "Because...", "When...", "If..." - these need to be attached to a main clause.

Lists without a sentence:
"For example, pollution, noise, and overcrowding." needs a main clause.

The Test

Ask: "Does this express a complete thought with a subject and verb?"

"Although many people disagree." - Incomplete. What happens despite their disagreement?

"Many people disagree." - Complete.

Common Fragment Starters to Watch

• Although / Though / Even though
• Because / Since / As (when meaning because)
• When / While / Before / After
• If / Unless
• Which / That / Who (relative clauses)

These words create dependent clauses that cannot stand alone.

Building Error-Free Sentences

The Band 7 descriptors mention "frequent error-free sentences." Here's how to produce them:

Strategy 1: Master Simple Sentences First

A simple sentence with no errors is better than a complex sentence with errors.

Error-free simple sentence:
"Technology has transformed education."

Complex sentence with errors:
"Technology has transformed education, which have made learning more accessible."

The first sentence contributes positively to your score. The second damages it.

Strategy 2: Use Complex Structures You're Sure About

Only use complex grammar you can control:

Relative clauses (if you know them well):

• "Students who use technology perform better in examinations."

Conditional sentences (if you're confident):

• "If governments invested more in education, literacy rates would improve."

Passive voice (when appropriate):

• "New policies have been implemented to address this issue."

Strategy 3: Proofread Specifically for These 5 Errors

In your final 2-3 minutes, scan specifically for:

1. Subject-verb agreement (especially with "is/are," "has/have")
2. Comma splices (comma + new sentence without conjunction)
3. Article usage (missing or unnecessary "the/a/an")
4. Tense consistency (especially in body paragraphs)
5. Sentence fragments (especially after "although," "because")

Error Priority for Band 7

If you're aiming for Band 7, prioritise in this order:

1. Subject-verb agreement - highly noticeable, frequent
2. Run-on sentences - affects coherence and grammar
3. Article errors - very common, adds to error count
4. Tense inconsistency - affects professionalism
5. Fragments - less common but damaging

Reducing errors in the first two categories alone can significantly improve your score.

Practice Exercise

Identify and correct the errors in this paragraph:

"Technology have changed education significantly. Many students now learn online, they find it more convenient. The advantages of online learning is numerous. Because students can study at their own pace. This flexibility mean that working professionals can also pursue education."

Errors:

1. "Technology have" - "Technology has" (subject-verb agreement)
2. "online, they" - "online; they" OR "online, and they" (comma splice)
3. "advantages...is" - "advantages...are" (subject-verb agreement)
4. "Because students can..." - Fragment - needs main clause
5. "flexibility mean" - "flexibility means" (subject-verb agreement)

Corrected version:
"Technology has changed education significantly. Many students now learn online**; they** find it more convenient. The advantages of online learning are numerous because students can study at their own pace. This flexibility means that working professionals can also pursue education."

Key Takeaways:

1. Focus on the five highest-impact grammar errors
2. Subject-verb agreement is the most common mistake - check every verb
3. Comma splices are easy to fix once you recognise them
4. Article errors add up - learn the three main rules
5. Maintain tense consistency within paragraphs
6. Proofread specifically for these five error types

You don't need perfect grammar for Band 7. You need fewer errors in the areas that matter most.

Want to identify the grammar errors holding back your score? We're currently in closed beta—join the waitlist to get early access to detailed grammar feedback on your essays.