Grammar mistakes in professional writing are like scuffs on a new pair of shoes. They are small, but people notice them. And once noticed, they colour everything else. A single misplaced apostrophe or the wrong “their” can make a reader question your attention to detail across the entire piece. In marketing copy, job applications, or client communications, that first impression matters enormously.
This article covers five of the most common grammar errors that undermine credibility, with clear explanations, examples, and quick fixes you can apply immediately.
1. Its vs. It’s
This is arguably the most common grammar mistake in English. The confusion is understandable because we are used to adding an apostrophe to show possession (the dog’s bowl, Sarah’s car). But “its” does not follow that rule.
The Rule
- Its (no apostrophe) = possessive form of “it.” Example: “The company updated its privacy policy.”
- It’s (with apostrophe) = contraction of “it is” or “it has.” Example: “It’s a great time to review your writing.”
Wrong vs. Right
| Incorrect | Correct | Explanation |
|---|---|---|
| The dog wagged it’s tail. | The dog wagged its tail. | Possession, not contraction |
| Its a beautiful day. | It’s a beautiful day. | Contraction of “it is” |
| The team confirmed it’s availability. | The team confirmed its availability. | Possession, not contraction |
Quick Fix
Before you write “its” or “it’s,” pause and ask yourself: can I replace this with “it is” or “it has”? If yes, use the apostrophe. If not, leave it out.
2. Your vs. You’re
Similar to its/it’s, this error comes from confusing a possessive with a contraction. In the rush of typing, it is easy to hit the wrong word, but the result stands out to any careful reader.
The Rule
- Your = possessive form of “you.” Example: “Please submit your report by Friday.”
- You’re = contraction of “you are.” Example: “You’re going to love the new design.”
Wrong vs. Right
| Incorrect | Correct | Explanation |
|---|---|---|
| Your the best candidate for this role. | You’re the best candidate for this role. | Contraction of “you are” |
| I value you’re opinion. | I value your opinion. | Possession |
Quick Fix
Substitute “you are” in your head. If it fits, use “you’re.” If it sounds wrong, use “your.”
3. There / Their / They’re
These three words sound identical but have completely different meanings. Mixing them up is one of the fastest ways to signal inexperience to a reader.
The Rules
- There = a place or an existence. Example: “The file is over there.” / “There are three options.”
- Their = belonging to them. Example: “The team submitted their proposal.”
- They’re = contraction of “they are.” Example: “They’re launching next week.”
Wrong vs. Right
| Incorrect | Correct | Explanation |
|---|---|---|
| They’re going to love there new office. | They’re going to love their new office. | “Their” shows possession of the office |
| Their are many reasons to apply. | There are many reasons to apply. | “There” introduces existence |
| I left the documents over their. | I left the documents over there. | “There” indicates a place |
Quick Fix
Check each usage: does it mean location or existence? Use “there.” Does it mean possession? Use “their.” Can it be replaced with “they are”? Use “they’re.”
4. Subject-Verb Agreement
Subject-verb agreement errors happen when the subject and verb do not match in number. Singular subjects need singular verbs; plural subjects need plural verbs. The error is most common when other words come between the subject and the verb, confusing the writer.
The Rule
A singular subject takes a singular verb. A plural subject takes a plural verb. Ignore any phrases that come between them.
Wrong vs. Right
| Incorrect | Correct | Explanation |
|---|---|---|
| The list of items are on the desk. | The list of items is on the desk. | The subject is “list” (singular), not “items” |
| Each of the employees have a badge. | Each of the employees has a badge. | “Each” is always singular |
| The team are meeting at noon. | The team is meeting at noon. | In US English, collective nouns are singular |
| Neither the manager nor the assistants was available. | Neither the manager nor the assistants were available. | The verb agrees with the nearest subject (“assistants”) |
Quick Fix
Identify the true subject of the sentence. Ignore prepositional phrases like “of the items” or “with the team.” Ask yourself: is the subject singular or plural? Then match the verb accordingly.
5. Comma Splices
A comma splice occurs when you join two independent clauses with only a comma. Independent clauses are groups of words that can stand alone as complete sentences. Connecting them with just a comma creates a grammatical error that makes your writing feel rushed.
The Rule
Two independent clauses cannot be joined with only a comma. You need either a period, a semicolon, or a comma followed by a coordinating conjunction (and, but, or, nor, for, yet, so).
Wrong vs. Right
| Incorrect (Comma Splice) | Correct | Method Used |
|---|---|---|
| The report is due Friday, we still have time to review it. | The report is due Friday. We still have time to review it. | Split into two sentences |
| I wanted to attend, my schedule was full. | I wanted to attend, but my schedule was full. | Added a conjunction |
| She finished the draft, she sent it for review. | She finished the draft; she sent it for review. | Used a semicolon |
Quick Fix
When you see a comma in your writing, check whether what comes before and after could each stand as a complete sentence. If yes, you have three choices: replace the comma with a period, add a coordinating conjunction after the comma, or use a semicolon.
Why These Mistakes Matter
You might be thinking that a single “its/it’s” error is not a big deal. In isolation, maybe it is not. But readers accumulate impressions. One mistake might go unnoticed, but two or three in the same document create a pattern. Research has shown that grammatically flawless content is perceived as more credible and more authoritative than writing with errors, even when the substance is identical.
For marketers and business writers, the stakes are higher. A landing page with a grammar mistake can reduce conversion rates. A proposal with an error can lose a client. An email with “you’re” where “your” belongs can undermine months of relationship building.
The good news is that these five errors are entirely fixable. Learn the rules, use a quick mental check before you write the word, and proofread your work before you hit send or publish. If you want extra assurance, run your text through the CopyRefine Filler Word Detector to catch not just filler words but also areas where your writing might need a second look.