Here's what surprises most students: you can nail your data description, use sophisticated vocabulary, and still get stuck at Band 6 because of grammar mistakes. But fix your grammar patterns, and you'll jump to Band 7.
The IELTS examiners aren't looking for perfection. They're looking for control. And that's the thing about Task 1—it's all about precision. You're describing numbers, trends, and comparisons. One grammar error doesn't kill you. But the same error repeated five times? That signals you don't understand the rule, and examiners drop your score accordingly.
This post walks you through the exact grammar mistakes that wreck Task 1 scores, shows you exactly how to spot them before you submit, and tells you which errors matter most for jumping between bands.
Task 1 isn't about storytelling or arguing a position. It's pure data analysis. You're showing the examiner one thing: can you control English grammar when describing factual information?
Here's the trap. One grammar error does damage in two directions. First, it directly lowers your Grammatical Range and Accuracy score, which is 25% of your writing mark. But second—and this is what most students miss—unclear grammar makes your data description confusing. If you can't control basic sentence structure, your Task Response score drops too. You lose marks on multiple criteria because of one grammar problem.
Take this: "Chart shows sales increased." That missing article ("the") looks tiny. But it tells the examiner you're not controlling basic English. Multiply that across 150 words, and you're looking at Band 5 or low Band 6. The examiner reads roughly one error per 30 words before they notice a pattern.
Quick tip: Task 1 is exactly 150 words minimum. At Band 7, examiners scan every sentence for grammatical control. One error per 30 words is roughly your tolerance before the pattern becomes obvious to the examiner and they mark you down.
Not all errors are created equal. Some look like careless typos. Others signal you're missing a core English rule. These are the common grammar mistakes in Task 1 that drag scores down fastest.
This is the biggest one. You pair a singular subject with a plural verb (or flip it around), and the examiner immediately flags it as a Band 5 control issue.
Wrong: "The data shows that consumption of renewable energy have increased significantly."
Right: "The data shows that consumption of renewable energy has increased significantly."
"Consumption" is singular, so it needs "has," not "have." One wrong verb and the examiner thinks your grammar control is shaky.
The trap: plural nouns that act as single units. "The number of visitors," "A series of events," "The majority of respondents"—all singular. Most students get this wrong because they focus on the plural noun after and forget the head noun is singular.
English articles are invisible in many languages. You naturally skip them when you speak. But Task 1 examiners notice immediately.
Wrong: "Chart illustrates that sales increased from 2015 to 2020."
Right: "The chart illustrates that sales increased from 2015 to 2020."
You need "the" because there's one specific chart in front of you. Without it, the sentence sounds like you're describing charts in general.
In Task 1, you'll reference data repeatedly: "The graph shows," "The chart reveals," "The table indicates," "The diagram demonstrates." Every single one needs "the." If you're missing articles in 6 or 7 sentences, that's a pattern that kills your score. This is one of the most common grammar mistakes in Task 1 responses.
Prepositions don't follow logic across languages. You might write "increase in 45%" when it should be "increase of 45%," and it sounds close enough to pass. But the examiner sees it as wrong.
Wrong: "There was an increase in 45% during the period."
Right: "There was an increase of 45% during the period."
With percentages and quantities, use "of." Task 1 is full of percentages and figures, so this error pattern shows up constantly in weak essays.
Other Task 1 preposition traps: "trend of" (not "trend in"), "difference between" (not "difference of"), "rise to" (reaching a level) vs. "rise by" (the amount it went up). Get these wrong and it's an immediate signal of control issues.
Task 1 deals with past or static data, so you should stay in past tense. But many students switch tenses mid-paragraph without realizing it.
Wrong: "The graph shows that sales increased in 2018, and then they rise sharply in 2019."
Right: "The graph shows that sales increased in 2018 and then rose sharply in 2019."
The chart is a fixed object showing past events. Everything should be past tense: increased, rose, fell, reached. When you flip to present ("rise"), the examiner reads it as a control error, not a stylistic choice.
One exception: if your chart shows current or ongoing trends, simple present is fine. "The chart shows that unemployment is rising" works. Just pick one tense and lock in for the entire essay.
You join two independent clauses with a comma instead of a period or connector. Instant Band 6 ceiling, sometimes lower.
Wrong: "The data reveals a sharp increase in mobile usage, this trend continues throughout the decade."
Right: "The data reveals a sharp increase in mobile usage, and this trend continues throughout the decade."
Or split it: "The data reveals a sharp increase in mobile usage. This trend continues throughout the decade."
For Band 7, you want complex sentences using dependent clauses (because, although, whereas, while, since). Comma splices signal Band 5/6 control, which is a major red flag. When examiners see multiple comma splices, they assume you don't understand sentence construction.
Let's get specific. IELTS Writing is marked on four criteria, each worth 25%: Task Response, Coherence & Cohesion, Lexical Resource, and Grammatical Range and Accuracy.
Here's what the band descriptors actually say:
Here's what kills most students: one grammar error doesn't just cost you points on that criterion. If your grammar is poor enough that meaning becomes unclear, your Task Response score suffers. If you can't control comma splices, your Coherence & Cohesion drops because your ideas aren't connecting logically. One error cascades across multiple marks.
You can't fix what you don't see. Here's a four-step process that catches most errors in about five minutes:
Read through once focusing only on subjects and verbs. Circle the main subject in each sentence. Does the verb match in number? Singular subject gets singular verb. This catches roughly 40% of errors.
Scan every sentence that mentions the chart, data, table, or diagram. Does it have "the"? You need "The graph shows," "The chart reveals," "The data illustrates." If you spot "Graph shows" without the article, you've found an error.
Ask yourself: when is this data from? Historical data means past tense throughout. Mark one color for past tense verbs, another for present tense. You should see almost all one color. Any surprises signal errors.
Read your entire essay aloud at normal speed. Your ear catches comma splices and awkward phrasing that your eyes miss. When you hear a sentence that makes you pause or re-read, that's probably an error.
These four checks take five minutes total. You don't need to be perfect, but you need consistent control. The examiner isn't looking for flawless writing. They're looking for evidence you understand English structure.
Pro tip: Do multiple focused passes instead of one sloppy read-through. One pass for subject-verb, one for articles, one for tenses. You'll catch 80% more errors this way because your brain isn't juggling five different rules at once.
Examiners understand you're writing under time pressure. You're rushing to hit 150 words, juggling data, managing grammar. A single article error in sentence 3? They gloss over it.
But if articles are missing in 8 different sentences? That's a pattern. That tells the examiner you don't understand the rule—you're not being careless, you're missing something fundamental. Patterns pull you down to Band 5.
When you review your essay, count how many times the same error appears. One or two times? That's careless. Three or more times? That's a pattern you need to fix before submitting.
Automated grammar checkers and IELTS writing correction tools catch obvious errors well. But they miss context-dependent mistakes that are common in Task 1.
A checker might not flag "consumption were" as wrong because "consumption" sits near other plural nouns. It might miss "increase in 45%" because "in" is technically a preposition. They're tools, not tutors.
Use an IELTS task 1 grammar checker to catch low-hanging fruit: comma splices, obvious subject-verb disagreements, spelling errors. Then manually review for the five error types we covered above.
Three-step process: write your essay, run it through a grammar checker for obvious mistakes, then do your four manual checks. This beats relying on any single tool alone.
Sample prompt: "The graph below shows electricity consumption in some countries between 1990 and 2010. Summarize the information and make any relevant comparisons."
Here's a weak response with multiple error types:
Weak version: "Graph illustrates electricity consumption across different nations from 1990 to 2010. Overall, consumption in most countries have increased during this period. France demonstrates the highest consumption levels, reaching approximately 450 units in 2010. UK consumption was rise from 300 to 350 units. The trends shows that industrial nations consume more electricity than developing countries. Importantly, Germany's consumption growth were more dramatic than other nations. In conclusion, data reveals a clear pattern; developed countries has higher consumption rates."
Error count in roughly 120 words:
That's 7 errors. Band 5 on grammar alone. Even if the data description were perfect, grammar is dragging the entire score down.
Now the corrected version:
Corrected version: "The graph illustrates electricity consumption across different nations from 1990 to 2010. Overall, consumption in most countries has increased during this period. France demonstrates the highest consumption levels, reaching approximately 450 units in 2010. UK consumption rose from 300 to 350 units. The trends show that industrial nations consume more electricity than developing countries. Importantly, Germany's consumption growth was more dramatic than other nations. In conclusion, the data reveals a clear pattern in which developed countries have higher consumption rates."
Same information, same data points. The only difference is grammar control. The examiner reads this and thinks Band 6 minimum, likely Band 7 if lexical resource and coherence are solid. That's the power of fixing grammar patterns.
You don't need perfect grammar for Band 7. You need controlled grammar. Here's the progression:
Band 5: Frequent errors that sometimes obscure meaning. You write things like "The increase of sales are" and "consumption show trends." Tenses shift randomly. The examiner has to re-read sentences to understand what you mean.
Band 6: Errors appear but they're mostly minor. Missing article here, preposition slip there. You attempt complex sentences but they're not always controlled. Tenses are mostly consistent. Meaning is clear even if grammar isn't smooth.
Band 7: Complex sentences with only occasional errors. You control articles, subject-verb agreement, and tenses reliably. You attempt varied structures and mostly succeed. Errors feel like careless slips, not pattern-based misunderstandings.
Band 8: Almost no errors. Complex structures controlled throughout. Flexibility in sentence construction. This is rare and honestly, you don't need it for most programs.
The jump from Band 6 to Band 7 happens when you eliminate error patterns. That's where most students get stuck. One missing article? Fine. Eight missing articles? That's the problem. Focus on stopping repetition, not achieving perfection.
Grammar control is 25% of your Task 1 score. It's not everything, but it's massive. The difference between Band 6 and Band 7 often comes down to whether you're making the same mistake repeatedly.
Before you submit your essay, run through those four checks. Spend five minutes hunting for the five error types we covered. One focused review catches most patterns and can lift you a full band.
If you're working on polishing your Task 1 response, consider checking the specific areas that pull scores down beyond just grammar. Our band score guides break down how structure and organization impact your overall mark. And if you're preparing for a timed test, our IELTS essay topics resource gives you practice with the kinds of graphs and data you'll see on test day.
Submit your Task 1 essay and get instant feedback on grammar errors, band score estimates, and line-by-line corrections. See exactly which patterns are holding you back with our free IELTS writing checker.
Check Your Essay