12 grammar mistakes that cost marks in IELTS and CELPIP writing (with fixes)
Grammar errors in IELTS and CELPIP writing are mostly systematic. Most candidates do not make a wide variety of random mistakes; they make the same dozen errors repeatedly, across every practice response and in the real exam. These errors are fixable faster than learning new grammar because the candidate already knows the underlying rule. The problem is inconsistent application under time pressure.
This guide covers the 12 most common errors, exactly why each one loses marks, and the specific fix for each. At the end, there is a breakdown of which errors matter most at each proficiency level, so you can prioritize the right fixes for your target score.
The 12 errors and their fixes
Error 1: Subject-verb agreement with collective nouns
| Wrong | "The government have decided to raise taxes." |
|---|---|
| Correct | "The government has decided to raise taxes." |
| Why it loses marks | Affects the Conventions criterion in CELPIP and the Grammatical Range and Accuracy criterion in IELTS. Collective nouns (government, committee, team, public) are singular in formal writing and take singular verbs. |
| Quick fix | In formal written English, treat collective nouns as singular. "The committee has approved the proposal." "The team is performing well." This is different from informal spoken British English, where collective nouns sometimes take plural verbs -- but in exam writing, singular is always the safer choice. |
Error 2: Article errors
| Wrong | "Problem is serious and needs immediate attention." |
|---|---|
| Correct | "The problem is serious and needs immediate attention." |
| Why it loses marks | Omitting "the" before a specific noun that both writer and reader can identify is a systematic article error that affects both Lexical Resource and Grammatical Range in IELTS, and Vocabulary and Conventions in CELPIP. |
| Quick fix | Use "the" when you and the reader both know which specific thing you mean: the problem you just described, the solution you are proposing, the situation you introduced in the previous sentence. Use "a" when you are introducing something for the first time. Use no article for general statements about categories: "Pollution is a serious concern" (pollution in general) vs "The pollution in this city is worsening" (specific, identifiable pollution). |
Error 3: Run-on sentences
| Wrong | "I studied all week, I passed the exam easily." |
|---|---|
| Correct | "I studied all week, and I passed the exam easily." or "I studied all week; I passed the exam easily." |
| Why it loses marks | Two independent clauses joined only by a comma (called a comma splice) is a sentence structure error that directly affects IELTS Grammatical Range and Accuracy, and CELPIP Conventions. |
| Quick fix | Three options: add a coordinating conjunction (and, but, so, yet, or, nor, for) after the comma; replace the comma with a semicolon; or break into two separate sentences. The coordinating conjunction option is the most readable in exam writing and signals sentence variety to the marker. |
Error 4: Sentence fragments
| Wrong | "Because the economy grew rapidly in the past decade." |
|---|---|
| Correct | "The country developed quickly because the economy grew rapidly in the past decade." |
| Why it loses marks | A dependent clause standing alone as a sentence has no main clause and therefore expresses an incomplete thought. This affects Task Achievement in IELTS (clarity of argument) and Content in CELPIP (completeness of response). |
| Quick fix | Clauses starting with because, although, since, while, when, if, unless, and despite are dependent clauses. They must attach to a main clause. If you write a sentence starting with one of these words, check that you have a second clause with a complete subject and verb. |
Error 5: Incorrect use of "however" as a conjunction
| Wrong | "I studied hard, however I did not pass." |
|---|---|
| Correct | "I studied hard; however, I did not pass." or "I studied hard. However, I did not pass." |
| Why it loses marks | "However" is a transitional adverb, not a coordinating conjunction. It cannot join two independent clauses with only a comma before it. This error is extremely common and directly affects Coherence and Cohesion in IELTS and Coherence in CELPIP. |
| Quick fix | Before "however": use a semicolon, or end the first sentence with a period. After "however": always use a comma. The pattern is: [independent clause]; however, [independent clause]. The same rule applies to "therefore," "moreover," "furthermore," "nevertheless," and "consequently." |
Error 6: Apostrophe errors with "its" and "it's"
| Wrong | "The policy has it's advantages and it's disadvantages." |
|---|---|
| Correct | "The policy has its advantages and its disadvantages." |
| Why it loses marks | This is a mechanical accuracy error that affects the Conventions criterion. Markers see it as a sign of weak proofreading, which reflects poorly on overall writing control. |
| Quick fix | The rule is straightforward: "it's" always means "it is" or "it has." If you can substitute "it is" and the sentence still makes sense, use "it's." If not, use "its" (the possessive). The government and its policies. The city is known for its parks. Test every "its" and "it's" by expanding it before submitting. |
Error 7: Tense inconsistency
| Wrong | "The company launched its new product last year. Customers respond positively and sales increase significantly." |
|---|---|
| Correct | "The company launched its new product last year. Customers responded positively and sales increased significantly." |
| Why it loses marks | Shifting tenses without reason creates confusion about when events occurred and makes the writing feel uncontrolled. This affects both Coherence and Grammatical Range in IELTS, and Coherence and Conventions in CELPIP. |
| Quick fix | Choose a primary tense for each paragraph and maintain it. For descriptions of past events, use past tense throughout. For general statements about ongoing situations, use present tense. Tense shifts are legitimate when describing a sequence of events in different time periods, but each shift needs a clear signal (a time expression, a transition, or a logical reason). |
Error 8: Parallel structure errors in lists
| Wrong | "She enjoys running, to swim, and going cycling on weekends." |
|---|---|
| Correct | "She enjoys running, swimming, and cycling on weekends." |
| Why it loses marks | Items in a list must use the same grammatical form. Mixing gerunds (running), infinitives (to swim), and gerund phrases (going cycling) shows inconsistent grammatical control. This affects Grammatical Range and Accuracy in IELTS and Conventions in CELPIP. |
| Quick fix | Before writing any list, decide on the grammatical form of the first item and use that form for every item that follows. All nouns, or all gerunds, or all infinitives, or all verb phrases. Reread every list before submitting and check that all items are in the same grammatical form. |
Error 9: Double negatives
| Wrong | "I don't have no time to complete the task." |
|---|---|
| Correct | "I don't have any time to complete the task." or "I have no time to complete the task." |
| Why it loses marks | Two negatives in the same clause cancel each other out logically and are non-standard in formal English. This is a grammatical accuracy error that can also affect the clarity of the intended meaning. |
| Quick fix | Use one negative per clause: either "not" with "any," or "no" alone. Never combine "not" with "no," "nothing," "nowhere," "nobody," or "neither." "There is not any solution" or "There is no solution," not "There is not no solution." |
Error 10: Preposition errors in fixed collocations
| Wrong | "The outcome depends of many factors." / "She is interested about the proposal." / "The plan consists from three stages." |
|---|---|
| Correct | "The outcome depends on many factors." / "She is interested in the proposal." / "The plan consists of three stages." |
| Why it loses marks | Preposition errors in fixed collocations affect the Lexical Resource criterion in IELTS and the Vocabulary criterion in CELPIP. These errors signal that vocabulary has been learned without its surrounding grammatical context. |
| Quick fix | Collocations are memorized, not derived from rules. Learn each expression as a fixed unit: "depend on," "interested in," "consist of," "responsible for," "capable of," "satisfied with," "result in," "contribute to," "focus on." When you encounter an unfamiliar expression, note its preposition alongside the word itself. Regular practice questions will reinforce these through context. |
Error 11: Dangling modifiers
| Wrong | "Having studied all night, the exam seemed easier than expected." |
|---|---|
| Correct | "Having studied all night, I found the exam easier than expected." |
| Why it loses marks | The introductory participial phrase must modify the subject of the main clause. In the wrong example, "having studied all night" appears to modify "the exam," which cannot study. This is a structural error that affects Grammatical Range and Accuracy in IELTS at higher band levels. |
| Quick fix | Whenever you use an introductory participial phrase (a phrase beginning with a verb ending in -ing or -ed), check that the subject of the main clause is the person or thing performing or experiencing the action in the phrase. If the phrase is "having studied all night," the subject of the main clause must be the person who studied. |
Error 12: Overuse of passive voice
| Wrong | "The problem was identified by researchers. A solution was proposed by the committee. The policy was then drafted by the government and was implemented by the relevant agencies." |
|---|---|
| Correct | "Researchers identified the problem. The committee proposed a solution, and the government drafted a policy that relevant agencies then implemented." |
| Why it loses marks | Passive voice is grammatically correct and appropriate in many contexts. Overuse, however, makes writing impersonal, evasive, and monotonous. Excessive passive construction affects Coherence and can flatten the sense of argument and agency that higher-band writing requires. |
| Quick fix | Use passive voice when: the agent (who did it) is unknown, irrelevant, or deliberately withheld; you are describing a process where the steps matter more than who performs them; or you want to emphasize the object rather than the subject. Use active voice when you want clarity about who does what, when you are building an argument, and in most cases where both options are possible. A good response will have both active and passive sentences -- the problem is using passive almost exclusively. |
Which errors matter most at your level
Not all 12 errors are equally damaging at every proficiency level. Knowing which errors are the highest-priority fixes for your target score helps you prepare more efficiently.
CLB 6 / IELTS Band 6 candidates
At this level, the errors that most directly limit the score are:
- Error 1 (subject-verb agreement): basic accuracy errors are heavily penalized at Band 6 and below.
- Error 2 (article errors): systematic article omission is one of the clearest markers of CLB 6 writing.
- Error 7 (tense inconsistency): this error signals limited grammatical control and affects both accuracy and coherence scores.
- Error 9 (double negatives): while less common in academic writing contexts, this error appears in spoken-influenced writing and reduces accuracy scores significantly.
Fixing these four errors consistently is typically enough to push a CLB 6 writer into CLB 7 territory.
CLB 8 / IELTS Band 7 candidates
At this level, basic accuracy errors are less common but structural errors become the ceiling:
- Error 3 (run-on sentences): extremely common at this level and directly caps the Grammatical Range score.
- Error 4 (sentence fragments): also common, particularly when candidates rush through subordinate clause constructions.
- Error 5 (however as conjunction): perhaps the single most common intermediate-level error seen in exam writing, and one of the most directly penalized.
- Error 11 (dangling modifiers): appears as candidates attempt more complex sentence structures. Fixing this separates CLB 8 from CLB 9 writing.
CLB 9+ / IELTS Band 8+ candidates
At the advanced level, errors are less about basic rules and more about precision and sophistication:
- Error 8 (parallel structure): inconsistent parallelism in lists and compound structures is the most visible marker of writing that is almost but not quite Band 8.
- Error 10 (preposition collocations): incorrect prepositions in fixed expressions are a consistent Lexical Resource deduction at higher levels.
- Error 12 (passive overuse): at Band 8+, the ability to vary sentence structure and voice deliberately is expected. Over-reliance on passive makes sophisticated ideas sound flat.
How to find your own systematic errors
Reading a list of grammar errors and recognizing them intellectually does not fix them in your writing. The gap between knowing a rule and applying it under time pressure is exactly where systematic errors live.
The most effective method for identifying your personal error patterns is structured practice with quality feedback. Here is the process:
This process works because it identifies the right target (your actual systematic errors, not a generic list) and applies focused correction before returning to timed practice. Most candidates who follow this process see measurable score improvement within 4-6 weeks.
The AI feedback tool on this site provides grammar error categorization with specific references to CELPIP and IELTS scoring criteria. It is designed for exactly this diagnostic purpose.
A practical note on proofreading under time pressure
One reason systematic errors persist in exam writing is that candidates run out of time to proofread or they proofread ineffectively. Reading your own writing silently, especially quickly, catches fewer errors than reading it differently.
Two strategies that work in exam conditions:
- Read sentence by sentence from the last sentence backwards. This breaks the narrative flow and forces you to see each sentence as a standalone unit, making structural errors easier to spot.
- Skim only for your known systematic errors. If you know from practice that you consistently make "however" punctuation errors, scan specifically for every "however" in the response and check the punctuation around it. This targeted scan takes 30 seconds and catches the errors that most affect your score.
Building two minutes of targeted proofreading into every timed practice session trains the habit so it becomes automatic in the actual exam. Candidates who practise proofreading as a skill, not as an afterthought, consistently find and fix more errors under real exam conditions.
Frequently asked questions
Which grammar errors matter most for IELTS Band 7?
At Band 7, the most commonly penalized errors are run-on sentences, sentence fragments, incorrect use of transitional adverbs like 'however' without proper punctuation, and dangling modifiers. These errors are not basic mistakes; they are intermediate-level problems that mark the boundary between Band 6 and Band 7 writing. Fixing them requires deliberate attention to sentence structure rather than vocabulary work.
How do grammar errors affect the CELPIP writing score?
CELPIP writing is scored on four criteria: Content, Coherence, Vocabulary, and Conventions. Grammar errors primarily affect Conventions (accuracy and range of grammar structures) but can also reduce Coherence scores if unclear sentences disrupt the flow of ideas. A single grammar error rarely drops a score by a full level, but systematic errors in the same category will consistently hold a candidate below their target CLB level.
Is it better to use simple grammar correctly or complex grammar with errors?
For IELTS and CELPIP, a mix of simple and complex structures used correctly scores higher than complex structures used with consistent errors. The marking criteria reward grammatical range AND accuracy. A response with mostly simple sentences but zero errors will outperform a response with attempted complex structures that are frequently incorrect. Build complexity gradually through practice rather than forcing it under exam pressure.
How can I find my own systematic grammar errors?
The most effective method is to submit 3-5 timed practice responses to a feedback source (AI feedback tool, experienced tutor, or structured peer review) and then look for patterns across all responses rather than individual corrections. If the same error type appears in three out of five responses, that is a systematic error. Targeted practice on that specific error type, followed by more timed writing, is more efficient than general grammar review.
Does passive voice hurt your IELTS or CELPIP score?
No. Passive voice is grammatically correct and is appropriate in many academic and formal writing contexts. The issue is overuse: relying on passive constructions throughout a response makes writing feel evasive and impersonal, which can affect the Coherence and Vocabulary criteria. Use passive voice when the agent is unknown or unimportant (for example, in describing a process), and use active voice when clarity about who does what is important for your argument.
Fix your grammar errors with targeted practice
The grammar lessons cover every structure in this guide with practice sentences and explanations tied to CELPIP and IELTS scoring criteria. The AI feedback tool identifies your systematic errors from timed writing so you know exactly what to fix.