IELTS grammar: Punctuation Rules

Punctuation is graded, not decorative. Under Grammatical Range and Accuracy, an examiner treats a comma splice, a misplaced apostrophe, or a missing pair of commas around extra information the same way they treat a wrong verb tense: as an accuracy error that caps how high a script can score, no matter how ambitious the vocabulary or how well-organised the argument. Candidates often assume punctuation is a Coherence and Cohesion issue at worst, something a marker might frown at but not actually penalise under Grammar. That assumption is wrong, and it matters because punctuation errors are unusually easy to fix once you know exactly which few patterns to check for. The error pattern specific to this topic is narrow: most IELTS punctuation mistakes cluster around exactly four things — comma splices, semicolon misuse, missing or wrongly placed commas around non-restrictive information, and apostrophe confusion — rather than punctuation errors being spread evenly across every mark on the keyboard. Learning those four patterns properly removes the majority of punctuation errors from a typical script in one pass, which is a very high return on a small amount of study time compared with almost anything else you could review before the exam.

Start with the comma splice, because it is the single most frequent punctuation error in Task 2 scripts. A comma splice joins two independent clauses — two word groups that could each stand alone as a complete sentence — using only a comma, with no conjunction and no semicolon: "The policy was popular, it failed to reduce costs." Both halves of that sentence are complete on their own, which means a lone comma cannot legally join them. There are three correct fixes, and which one you choose changes the emphasis slightly. You can split the comma splice into two separate sentences: "The policy was popular. It failed to reduce costs." You can join the two clauses with a semicolon if they are closely related in meaning: "The policy was popular; it failed to reduce costs." Or you can add a coordinating or subordinating conjunction that makes the logical relationship explicit: "The policy was popular, but it failed to reduce costs" or "Although the policy was popular, it failed to reduce costs." The third option is usually the strongest for IELTS, because it does two jobs at once — it fixes the punctuation error and it also names the logical relationship between the two ideas, which is exactly what Coherence and Cohesion rewards.

A run-on sentence is the comma splice's more extreme cousin: two or more independent clauses jammed together with no punctuation at all. "The policy was popular it failed to reduce costs the government scrapped it after a year" is three complete sentences with nothing separating them, and it is genuinely difficult for a reader to parse on a first pass. Run-ons tend to appear under time pressure, when a candidate is thinking faster than they are writing and simply forgets to punctuate between ideas that arrived together in their head. The fix is identical to the comma splice fix: find each independent clause, and either separate them into sentences, join them with a semicolon, or connect them with a conjunction. A quick self-check that catches both errors: read each sentence in your script and ask whether it secretly contains two or more complete sentences glued together without a proper joiner. If it does, decide deliberately how you want to join or separate them rather than defaulting to a comma out of habit.