IELTS Writing Mistakes Thai Speakers Make: 7 L1 Patterns Costing You Marks
Reading time: 12 minutes
If you are a Thai speaker preparing for IELTS, you have probably had this frustrating experience: your ideas are clear, your vocabulary is reasonable, but your Writing score stays stuck at Band 5 or 5.5. You re-read your essay and it sounds fine to you. So what is going wrong?
The answer lies in something linguists call L1 interference — the way your first language (Thai) shapes the way you produce English. Thai and English are structurally very different languages, and those differences create predictable, repeatable error patterns in your IELTS writing. The good news is that once you understand why you make these mistakes, you can start fixing them systematically.
This guide walks through seven specific interference patterns, explains the linguistic reason behind each one, and gives you concrete strategies to overcome them.
1. Missing Articles (a, an, the)
Why Thai Causes This
Thai has no article system at all. There is no Thai equivalent of "a," "an," or "the." In Thai, you simply say the noun directly — "หนังสืออยู่บนโต๊ะ" (book is on table) is perfectly grammatical. Classifiers exist in Thai, but they serve a different function from English articles.
This means your brain has no instinct for when English requires an article and when it does not.
What It Looks Like
Incorrect: Government should invest in education to solve problem of unemployment.
Correct: The government should invest in education to solve the problem of unemployment.
Incorrect: She wants to become doctor in future.
Correct: She wants to become a doctor in the future.
How to Practise
After writing any paragraph, go back and check every noun. Ask three questions: Is it countable? Is it specific or general? Has it been mentioned before? These three questions cover most article decisions. Build a habit of doing this as a dedicated editing pass.
2. Missing Plural Markers
Why Thai Causes This
Thai does not mark plurality on nouns. The word "หนังสือ" means both "book" and "books" — context or a number word makes the meaning clear. English, by contrast, demands that you mark every countable noun as singular or plural, every single time.
Because Thai speakers never need to think about plural endings, the -s or -es suffix often gets dropped in English writing.
What It Looks Like
Incorrect: There are many advantage to studying abroad, but also some disadvantage.
Correct: There are many advantages to studying abroad, but also some disadvantages.
Incorrect: Student in developing country often lack resource.
Correct: Students in developing countries often lack resources.
How to Practise
When editing, look for quantity signals: many, some, several, few, most, all, two, three. Every noun following these words must be plural. Also check nouns after "are" and "were" — they are almost always plural.
3. Tense Errors (Missing or Wrong Tense)
Why Thai Causes This
Thai verbs do not conjugate at all. The verb "ไป" (go) stays the same whether you are talking about the past, present, or future. Thai uses context words like "แล้ว" (already), "จะ" (will), or "กำลัง" (currently) to indicate time, but the verb form never changes.
English requires you to change the verb itself — go, went, gone, going, goes — and IELTS examiners pay close attention to whether you control tense accurately.
What It Looks Like
Incorrect: Last year, the government introduce a new policy and many people oppose it.
Correct: Last year, the government introduced a new policy and many people opposed it.
Incorrect: If the trend continue, the situation get worse by 2030.
Correct: If the trend continues, the situation will get worse by 2030.
How to Practise
Before writing, decide the main tense for each paragraph. If you are discussing a past event, every verb in that section should be past tense unless you have a specific reason to switch. After writing, underline every verb and check it against the time frame of the paragraph.
4. Subject-Verb Agreement
Why Thai Causes This
Because Thai verbs do not change form at all, there is no concept of subject-verb agreement. You never need to distinguish between "he go" and "he goes" in Thai — the verb is always the same. In English, third-person singular subjects (he, she, it, the government, a student) require an -s on present-tense verbs.
This pattern is closely related to the tense issue above, but it catches Thai speakers even when they remember to use present tense.
What It Looks Like
Incorrect: Technology have a significant impact on education. It change the way students learn.
Correct: Technology has a significant impact on education. It changes the way students learn.
Incorrect: Each student need to develop their own study plan.
Correct: Each student needs to develop their own study plan.
How to Practise
During your editing pass, draw an arrow from every verb to its subject. Check: is the subject singular or plural? If singular (and present tense), the verb likely needs -s or -es. Pay special attention to "each," "every," "everyone," "nobody" — these are all grammatically singular even though they feel plural.
5. Word Order Problems
Why Thai Causes This
Thai generally follows a Subject-Verb-Object word order like English, but there are important differences in how modifiers are placed. In Thai, adjectives come after the noun: "บ้านใหญ่" is literally "house big." Relative clauses and possessives also follow different ordering rules.
These differences can cause Thai speakers to produce awkward or non-standard English word order, especially in complex sentences.
What It Looks Like
Incorrect: The problem main is that education system does not teach skill practical.
Correct: The main problem is that the education system does not teach practical skills.
Incorrect: People living in city big often have life stressful.
Correct: People living in big cities often have stressful lives.
How to Practise
Remember this rule: in English, adjectives almost always go before the noun. When you catch yourself writing "noun + adjective," reverse the order. For longer descriptions, follow the pattern: opinion-size-age-shape-colour-origin-material-purpose + noun.
6. Overly Informal Register
Why Thai Causes This
Thai has a complex politeness system based on particles (ครับ/ค่ะ) and pronoun choice, but the vocabulary and sentence structure used in formal and informal Thai are not as sharply divided as in English. Many Thai learners of English pick up conversational English first — from social media, movies, or speaking practice — and carry that informal style into academic writing.
IELTS Task 2 requires a formal academic register, and examiners specifically mark you down for informal language.
What It Looks Like
Incorrect: Lots of kids these days are super addicted to their phones and stuff.
Correct: A significant number of young people today are increasingly dependent on mobile devices.
Incorrect: The government should totally fix this problem ASAP.
Correct: The government should address this issue as a matter of priority.
How to Practise
Build a personal "swap list" of informal words and their formal equivalents. Common swaps: lots of → a significant number of, kids → children/young people, get → obtain/receive, thing → factor/aspect, good → beneficial, bad → detrimental. Before submitting, scan your essay for any word you would use in a text message — it probably needs upgrading. For more on achieving the right academic tone, see our guide on hedging language in IELTS writing.
7. Run-On Sentences and Missing Connectors
Why Thai Causes This
Thai writing tolerates much longer sentences connected by commas or simply strung together with minimal punctuation. Thai readers parse meaning from context and particles rather than strict punctuation rules. When Thai speakers write English, they often produce very long sentences joined by commas where English requires full stops, semicolons, or coordinating conjunctions.
IELTS examiners assess Coherence and Cohesion as a separate scoring criterion, and run-on sentences directly hurt this score.
What It Looks Like
Incorrect: Many students want to study abroad, they believe it will improve their career prospects, however the cost is very high, not everyone can afford it.
Correct: Many students want to study abroad because they believe it will improve their career prospects. However, the cost is very high, and not everyone can afford it.
Incorrect: The government should increase funding for education, this will help create more jobs, the economy will improve.
Correct: The government should increase funding for education. This investment will help create more jobs, which in turn will improve the economy.
How to Practise
Apply the "one idea, one sentence" rule. If a sentence contains two or more complete thoughts (each with its own subject and verb), it probably needs to be split. Read your essay aloud — wherever you pause naturally for breath, you likely need a full stop or linking word. For a deeper look at how grammar errors affect your band score, see our guide on the 5 grammar errors that cost you the most marks.
How to Practise: A System That Works
Knowing the seven patterns above is only the beginning. Here is how to turn that knowledge into real improvement.
Build a Personal Error Checklist
After learning these patterns, create a checklist with all seven items. After writing every practice essay, run through the checklist one item at a time. Do not try to check everything at once — do seven separate passes if needed. Speed will come with practice.
Keep an Error Log
Every time you get feedback (from a teacher, an AI tool, or self-editing) that highlights one of these errors, write it down:
- The incorrect sentence
- The corrected version
- Which of the seven patterns it falls under
After logging 20-30 errors, you will see which patterns are your biggest weaknesses. Focus your energy there.
Use Targeted Drills
Do not just write more essays. Spend 15 minutes a day on focused exercises:
- Articles: Take a paragraph from the Economist or BBC and remove all articles. Put them back from memory, then check.
- Plurals: Write 10 sentences using "many," "several," and "few" — check every noun.
- Tenses: Rewrite a present-tense paragraph in past tense, verb by verb.
- Agreement: Write 10 sentences with tricky singular subjects (everyone, each, the government).
The Two-Pass Writing Strategy
Under exam conditions, do not try to monitor all seven patterns while developing your argument. Instead:
- First draft (30 minutes): Focus entirely on ideas, structure, and vocabulary
- Editing pass (8-10 minutes): Run through your checklist, fixing errors pattern by pattern
This approach accepts that your L1 instincts will produce errors and builds in a structured correction stage.
The Encouraging Reality
These seven error patterns are not signs of poor English ability. They are the predictable result of your brain applying Thai grammar rules to English writing. Every Thai speaker faces them, and every one of these patterns is fixable with targeted practice.
The students who break through from Band 5.5 to Band 7 are not the ones who write the most essays. They are the ones who identify their specific L1 interference patterns and attack them one at a time.
Want personalised feedback that identifies your L1 interference patterns automatically? We are currently in closed beta — join the waitlist to get early access to targeted diagnosis and adaptive learning paths built for your specific error profile.