Short answer: The mistakes that hold Task 1 at Band 6 are predictable: no clear overview, listing every figure, speculating about causes, copying the prompt, drifting tenses, inventing precision, missing categories, and under-length answers. All eight are mechanical habits — findable in your own answers and fixable within weeks.
Task 1 is the most formulaic part of IELTS Writing, which cuts both ways: the structure is learnable in a week, and the mistakes are so consistent that examiners can often predict a script's band from its first two paragraphs.
This post ranks the eight most expensive mistakes, explains what each one costs in descriptor terms, and ends with a weak opening rewritten into a full corrected model. It is the trouble-shooting companion to our chart-specific guides — line graphs, bar charts, pie charts and tables.
What are the most common mistakes in IELTS Writing Task 1?
Here is the ranked list. The first two account for more capped scores than the other six combined.
| # | Mistake | What it costs | Fix |
|---|---|---|---|
| 1 | No clear overview | Task Achievement generally capped around Band 5 | One or two no-figure sentences after the introduction, flagged with "Overall" |
| 2 | Listing every data point | "Mechanical recounting" — TA held at 5–6 | Select extremes, changes and exceptions; group the rest |
| 3 | Speculation and opinion | Irrelevant content weakens TA | Describe what the visual shows; give no causes or views |
| 4 | Copying the prompt | Copied words uncounted; no paraphrase shown | Reword the introduction fully |
| 5 | Tense drift | Grammar accuracy drops | Set the tense from the dates and hold it |
| 6 | Invented precision | Inaccurate data reporting | Use "approximately", "just under" for between-gridline values |
| 7 | Missing a category or visual | Incomplete coverage of requirements | Mention every line, bar, segment or chart at least once |
| 8 | Under 150 words | TA penalty for insufficient coverage | Aim for 160–190 words |
Why does a missing overview cap your score?
Because the descriptors are explicit about it. Band 5 Task Achievement includes "no clear overview"; Band 6 requires an overview; Band 7 requires a clear one. No other single sentence in the report has a band boundary named after it.
The insidious version is the buried overview — big-picture observations scattered through the bodies where the examiner must assemble them. If your main trends are not gathered into one flagged place, you are asking a time-pressured reader to do your selection for you.
The fix costs one minute: after the introduction, write "Overall, ..." and state the two or three biggest patterns with no figures. The complete method is in our overview sentence guide.
Why is describing every number a mistake?
Because the task instruction says "select and report the main features", and the Band 5 descriptor names the failure exactly: recounting detail mechanically. An answer can be 100% accurate and still sit at Band 5 if it demonstrates no judgement about what matters.
The tell-tale shape is the chronological crawl — "In 2004 it was 25%. In 2006 it rose to 30%. In 2008 it reached 34%..." — or, on tables, the row-by-row recital of every cell.
The repair rule: every figure you quote must be doing a job — an extreme, a start or end point, a biggest change, an exception, or one half of a comparison. A number with no job stays in the chart.
Why can't you give opinions or reasons in Task 1?
Task 1 is a report, not an essay. The instruction asks you to summarise and compare information; it never asks why the data moved or whether the trend is good. "This is because of smartphone adoption" and "worryingly, usage doubled" are both off-task — the first invents evidence, the second inserts a view.
Speculation costs twice: the sentence earns nothing under Task Achievement, and it displaces words that a real feature needed. In a 170-word report, a three-line explanation of causes is nearly a fifth of your budget spent scoring zero.
Keep analysis for Task 2, where it is the whole job. In Task 1, the most analytical thing you can legally do is a sharp comparison — "cycling almost trebled while bus use declined" — which is also exactly what the descriptors reward.
The smaller leaks: tense, precision, coverage, length
Tense drift. Past years take the past simple; a range ending now takes the present perfect; projections take "is expected to". Pick the frame from the dates before writing and hold it — switching mid-report is one of the most common accuracy flags in Task 1 scripts.
Invented precision. If the bar ends between gridlines, it is "just under 6 million", not "5.8 million". Approximation language is accurate; invented decimals are errors.
Coverage gaps. Every line, bar, segment, row and — on mixed tasks — every visual must appear at least once, even inside a grouped sentence. Skipping one is an incomplete answer, not tight selection.
Length. Under 150 words is penalised; far over 200 usually means selection failed. The 160–190 band is where selective, complete answers naturally land.
A weak answer corrected: before and after
The task below was written for this article as a teaching example in the exam's style — not a real or predicted question. "The line graph shows average daily water consumption per person in one country between 1994 and 2024."
A typical Band 5-6 script opens like this: "The line graph shows average daily water consumption per person in one country between 1994 and 2024. In 1994 it was 150 litres. In 1999 it was 165 litres. In 2004 it was 180 litres. This is probably because the population grew." Prompt copied, data crawled, cause invented — mistakes 1, 2, 3 and 4 in four sentences.
Corrected model answer (172 words):
The line graph shows how much water the average person used per day in one country over the thirty years from 1994 to 2024.
Overall, daily consumption rose markedly for the first half of the period and then declined almost as steeply, ending only slightly above its starting level. The peak came in 2009, the midpoint of the timeframe.
In 1994, the average person used 150 litres per day. This figure climbed steadily over the following fifteen years, reaching a high of 195 litres in 2009 — an increase of roughly a third on the starting value.
The trend then reversed. Usage fell consistently across the next fifteen years, dropping below 170 litres in 2017 and finishing the period at 155 litres in 2024. Although this final figure remained marginally higher than that of 1994, it represented a decline of 40 litres, or around a fifth, from the peak.
What changed. The introduction now paraphrases ("water consumption per person" becomes "how much water the average person used"). A flagged, figure-free overview appears.
The thirty years collapse into two movements with five working figures — start, peak, a threshold, the end, and the fall from peak. And the speculation is simply gone: the corrected version explains nothing and describes everything.
How do you check your own Task 1 answers for these mistakes?
Audit every practice answer against the ranked table before you count it as practice: overview present and flagged? Every figure doing a job? Zero causes and opinions? One tense frame? Everything covered, over 150 words?
The audit catches the structural mistakes; the ones you cannot see in your own writing — error density, whether the overview reads as "clear" — are what the IELTS Writing Checker measures, scoring each answer against the official criteria so the same mistake stops appearing twice.
Run that loop weekly, alongside the plan in our writing improvement guide, and Band 6 habits disappear the way they formed: mechanically.