IELTS Writing Task 1 Grammar Errors Checker and Correction Guide

Let's get real: grammar mistakes in Task 1 will cost you 0.5 to 1.5 band points. That's the difference between a 6.5 and a 7.0, or between 7.0 and 7.5. We're not talking small slip-ups here. The IELTS band descriptors for Grammatical Range & Accuracy at Band 7 demand "generally accurate" writing with only "rare errors that do not impede communication." Band 6? That accepts "frequent errors" that occasionally confuse the reader.

Here's what most students miss: you probably know these grammar rules already. The problem isn't knowledge—it's that you don't catch your own mistakes when the clock is running. Task 1 gives you 20 minutes to describe a chart, write a letter, or explain a process. You're racing. Your brain skips right over errors that your eyes would catch if you had time to slow down.

This guide shows you exactly which grammar mistakes tank Band 7+ scores, how to spot them in your own work using an IELTS writing checker mindset, and how to fix them before the examiner reads them.

The Four Grammar Mistakes That Cost You the Most in Task 1

Not every grammar error hits equally hard. Some barely dent your score. Others drop you immediately because they break rules that even Band 6 writers should nail.

These are the four common grammar mistakes that hurt your score the most in Task 1:

1. Subject-verb disagreement: "The data shows" vs. "The data show" (confuses meaning and looks careless)
2. Sentence fragments and run-ons: Incomplete thoughts or sentences smashed together without proper punctuation (screams Band 5 writing)
3. Tense inconsistency: Jumping between past and present in one paragraph for no reason (confuses the reader about timing)
4. Article misuse: Missing or extra "a/an/the" (less damaging than the others, but common across all bands)

Why these four? Because they either change what you mean, break sentence structure completely, or signal that you don't understand basic grammar rules. A clunky word choice might cost you 0.1 band points. These cost you 0.5 or more.

Subject-Verb Disagreement: Why "The Data Show" Actually Matters

This one trips up more IELTS writers than almost any other rule, especially in Task 1 where you're dealing with data constantly.

The rule itself is simple: plural nouns take plural verbs. "Data" is plural (the singular is "datum"). Same with "The number of people"—the core noun is "number," which is singular, so your verb has to be singular too.

Now look at this one carefully:

Your subject is "number," not "employees." One number equals a singular verb: "has." Even strong writers miss this one because your brain locks onto "employees" (plural) and forgets what the actual subject is.

Sentence Fragments and Run-Ons: The Structure Killer

A fragment is an incomplete thought punctuated as a sentence. A run-on is two independent clauses crammed together without proper punctuation. Both scream "Band 5 writer" to an examiner.

Here's a real Task 1 letter example:

"Which arrived last week" is a fragment. It's a dependent clause that's been cut loose. It needs to attach to an independent clause. Here's the fix:

Now here's a run-on. Two complete sentences jammed together with just a comma (called a comma splice):

You need either a period, semicolon, or a conjunction to join them:

Tense Inconsistency: Stay Consistent Within Your Paragraph

This one's sneaky but deadly for your score. IELTS examiners expect consistency. If you're describing a chart from 2015, stick with past tense throughout that paragraph. Flip to present tense without reason, and it looks like careless writing, not sophisticated variety.

In Task 1 context: you're describing data. That data is from the past. Use past tense consistently:

See it? "Produced" (past), "represents" (present), and "have stagnated" (present perfect) all mixed together without reason. Here's the correction:

All past. Consistent. Looks polished.

One exception: if you're stating something that's universally true today, present tense works. "Renewable energy is more sustainable than fossil fuels." That's a fact, so present tense fits. But once you've anchored yourself to a specific time period (2015, last year, the study period), stay there.

Article Errors: Small but Frequent in Task 1 Letter Writing

Articles (a, an, the) won't demolish your score like fragments do, but they're the most commonly marked error in Band 6 writing. They hurt you through sheer repetition.

The two biggest Task 1 article mistakes:

1. Missing "the" with specific nouns:

You're talking about a specific chart (the one in front of you), so use "the."

2. Wrong article with countable and uncountable nouns:

"Data" is uncountable (plural as a mass noun), so no "a/an." Use "the" or nothing, depending on specificity.

How to Become Your Own IELTS Grammar Correction Tool

You won't have Grammarly in the exam room. You need to be your own editor. Here's the process that actually works:

Step 1: Write fast (first 15 minutes). Don't edit as you go. Get your ideas down. Speed matters in Task 1 because you've only got 20 minutes total.

Step 2: Read aloud (last 3-4 minutes). Yes, this sounds weird, but it works. Your ear catches things your eyes miss. You'll hear run-ons because you'll run out of breath. You'll hear tense shifts because they'll sound jarring.

Step 3: Check the danger zones (last 1-2 minutes). Don't read every word. Focus only on sentences where you see subject-verb pairs and places where you changed tense. Look extra hard at sentences starting with dependent clauses (words like "which," "because," "although"). That's where errors hide.

Step 4: Underline and circle. In two minutes, scan your work and underline every subject and circle every verb. Do they match in number and tense? This visual check catches about 60% of the mistakes most writers make.

Band 7 vs. Band 6: What the IELTS Writing Correction Reveals

The IELTS band descriptors are specific. Here's what separates Band 7 from Band 6:

Band 7: "Uses a range of structures with generally accurate spelling and punctuation. Grammar is generally accurate. Errors are rare and do not impede communication."

Band 6: "Uses a range of structures. Frequent errors with spelling and punctuation. Grammar is generally accurate. Errors sometimes impede communication."

What does "errors that impede communication" actually mean? It means the examiner stops reading and thinks, "Wait, what did they mean?" Subject-verb disagreement, run-ons, and tense chaos do this. Article errors rarely do.

Real numbers: Band 7 essays typically have 1-3 grammar errors per 150 words. Band 6 essays have 5-8 errors per 150 words. That difference? It's 20 minutes of careful proofing versus none.

Which Writing Correction Tools Actually Help

You've probably tried Grammarly. It's useful, but it's not built for IELTS specifically. Here's why: it's trained on general English and American conventions. It sometimes flags things as wrong that are right in British English (which IELTS uses). It also misses context. An IELTS examiner understands your reasoning; Grammarly just sees a rule.

What actually helps? Targeted practice with Band 7-8 samples. Write a Task 1 response, then compare it word by word to the Band 7-8 samples Cambridge publishes. Ask yourself: "Did I use that structure? Could I? Why or why not?" This teaches your brain patterns faster than any rule.

Then use an IELTS-specific writing checker that gives feedback tailored to the band descriptors and IELTS letter or chart requirements. A standard grammar correction tool won't understand what IELTS examiners prioritize. They just know generic grammar rules. An IELTS writing evaluator understands the specific criteria: coherence, lexical range, grammatical accuracy, and task achievement.

Your 30-Second Error Checklist Before Submitting

In the exam with 30 seconds left? Use this priority list:

1. Does every sentence have a subject and a verb? (Eliminate fragments)
2. Are subject and verb in the same sentence? (Eliminate run-ons)
3. Does the verb match the subject in number? (Singular equals singular verb)
4. Did I switch tense without reason? (One paragraph equals one tense)
5. Did I use "the" correctly when naming specific things? (The chart, the table, the letter)

If all five pass, you're minimum Band 6 grammar territory. If they pass cleanly with no corrections, you're solid Band 7 territory.

If you're working on improving your overall Task 1 skills, our guide on fixing weak overview paragraphs covers the other major band-score killer alongside grammar.