The Most Common Grammar Mistakes in IELTS Writing (and How to Fix Them)

Of the four Writing criteria, Grammatical Range and Accuracy is the one most candidates lose marks on without ever knowing why. It is worth 25% of your Writing band, and the descriptors are blunt: to reach Band 7 you need "frequent error-free sentences" and only occasional slips. Most Band 6 essays are not badly written — they are competent essays undermined by the same small set of repeated errors. This guide lists the mistakes examiners see most often, why each one costs you, and exactly how to fix it.

Why grammar caps so many essays at Band 6

The Band 6 descriptor allows a "mix of simple and complex sentence forms" but expects errors that "rarely reduce communication." Band 7 demands the opposite balance: mostly accurate sentences with errors that are the exception, not the rule. The difference is rarely one dramatic mistake. It is a comma splice here, a missing article there, a wrong preposition in the next paragraph — small, frequent, and entirely fixable. Clean up the recurring ones and your accuracy climbs a whole band without you writing a single harder sentence.

1. Articles (a, an, the) — or missing them entirely

Articles are the single most common error for candidates whose first language does not use them. Two patterns dominate:

• Dropping the article before a singular countable noun. "Government should build more houses" needs The government. A singular countable noun almost always needs an article or another determiner.
• Adding "the" before a general plural or uncountable noun. "The pollution is a serious problem" and "The children learn faster" are wrong when you mean people or things in general. Say Pollution is a serious problem and Children learn faster.

Fix: when you write a noun, ask two questions — is it countable, and do I mean a specific one or things in general? Specific singular takes the; general plurals and uncountables usually take no article at all.

2. Subject-verb agreement

The verb must match the subject in number, and long sentences make this easy to lose. "The number of students have increased" is wrong — the subject is number, which is singular, so it is has increased. Watch especially for:

• Words that come between the subject and verb: "A range of measures is needed," not are.
• Uncountable nouns that look plural: information, advice, research, knowledge all take a singular verb.
• "Each," "every," and "one of" — always singular: "Each of these factors affects the result."

3. Run-on sentences and comma splices

This is the error that most often separates Band 6 from Band 7, because it appears exactly when a candidate reaches for a "complex" sentence. Joining two full clauses with only a comma is a comma splice: "Cars cause pollution, they should be taxed." Two independent clauses need one of three things: a full stop, a semicolon, or a coordinating conjunction (and, but, so). Correct: "Cars cause pollution, so they should be taxed."

Fix: if you can put a full stop where your comma is and both halves stand alone as sentences, you have a splice. Add a linking word or split the sentence.

4. Prepositions

Prepositions rarely stop the examiner understanding you, but a scatter of wrong ones drags down accuracy. The common offenders in Task 2 and Task 1:

• discuss takes no preposition — "discuss about the issue" is wrong.
• An increase or a rise is in something and of an amount: "a rise in unemployment," "a rise of 10%."
• affect takes no to; you have an effect on something.
• You are responsible for something, dependent on it, and it has an impact on people.

5. Verb tense and time markers

In Task 2 the default is the present simple for general truths. Problems appear when candidates drift between tenses in one sentence, or use the wrong tense for the data in Academic Task 1. A chart showing 1990 to 2010 is finished time, so it needs the past simple: "The figure rose sharply," not rises. A projection to 2035 needs a future form: "numbers are expected to rise." Match your tense to the time shown, and keep it consistent within each sentence.

6. Countable and uncountable nouns

Several very common IELTS words are uncountable and take no plural and no a/an: information, advice, research, equipment, knowledge, traffic, money, work. "Many informations" and "an advice" are both wrong. Say a great deal of information or a piece of advice. This overlaps with articles and subject-verb agreement, which is why fixing it lifts several errors at once.

7. Word form confusion

Using the noun where you need the adjective, or the adjective where you need the verb, is scored under grammar and vocabulary together. Common mix-ups: economic (relating to the economy) versus economical (cheap to run); advise (verb) versus advice (noun); affect (verb) versus effect (noun). "This will benefit to society" should be "This will benefit society" — benefit is already the verb.

The three-minute proofreading routine that saves your band

Most of these errors are ones you can already correct when you slow down — you simply do not see them while composing. So reserve the last three minutes of each task to hunt for them deliberately, in this order:

1. Articles and plurals. Point at every noun and check: does it need a, the, or nothing? Should it be singular or plural?
2. Verbs. Does each verb agree with its subject, and is the tense right for the time you mean?
3. Sentence boundaries. Look at every comma between two full clauses and fix any splices.

Checking one category at a time catches far more than reading through once for "anything wrong."

How to practise until the errors disappear

Grammar improves fastest from your own mistakes, not from grammar books. Write one timed essay, then get a criterion-by-criterion breakdown from our free AI IELTS essay checker, which flags your grammar errors with corrections so you can see which ones you repeat. Keep a short list of your personal recurring three or four — most people have the same handful every time — and proofread specifically for those. For the paragraph framework that gives your accurate grammar something worth saying, see our guide to Band 7 Task 2 structure, and once you have a Writing estimate, run all four skills through the band score calculator to see what a cleaner grammar band does to your overall result.