Ever stopped mid-sentence thinking, “Wait, did I just write ‘that that’?” You’re not alone.
At first glance, “that that” looks like a typo or a grammatical slip-up. But here’s the twist—it’s often 100% correct.
The trick lies in understanding why it’s correct, when it’s not, and how to use it without confusing your readers.
Let’s unpack this puzzling pair and master the logic behind it.
Understanding the Grammar Behind “That That”
Before you can decide whether “that that” belongs in your sentence, you have to understand what “that” actually does in English grammar. Surprisingly, it wears several hats.
| Function | Role in Sentence | Example |
|---|---|---|
| Conjunction | Connects clauses or introduces reported speech | I said that you were right. |
| Determiner | Points to a specific thing | That car is mine. |
| Pronoun | Refers to a previously mentioned idea or object | That was amazing! |
| Adjective Clause Marker | Introduces clauses describing nouns | The book that you gave me was great. |
When these roles overlap—especially when “that” acts as both a conjunction and a pronoun—you can end up with a legitimate “that that” structure.
Example:
I know that that rule applies here.
- The first “that” introduces a subordinate clause.
- The second “that” is a pronoun referring to a specific rule.
Grammatically solid. Stylistically clunky—but not wrong.
When “That That” Is Actually Correct
Let’s get this straight: “that that” is not always a mistake. There are genuine scenarios where it’s the only grammatically accurate choice.
1. Clause Connection + Reference
She said that that was her favorite movie.
- First “that” introduces what she said (a conjunction).
- Second “that” replaces “movie” (a demonstrative pronoun).
Both serve clear grammatical roles—each earns its place.
2. Reported Speech
He explained that that was the reason for his decision.
Writers often drop one “that,” but formally, this version clarifies cause and reference precisely.
3. Academic and Legal Writing
In precise, formal, or legal contexts, “that that” can prevent ambiguity.
The court ruled that that statute was no longer enforceable.
Legal writing values clarity over rhythm—so repetition often wins.
Quick Fact
In linguistic studies, “that that” appears frequently in academic English. A 2022 grammar corpus analysis found that the construction occurs over 18 times per million words in scholarly writing—far from rare!
When “That That” Becomes a Problem
Although grammatically correct, “that that” can easily trip readers. The human brain loves rhythm and flow—two things disrupted by back-to-back repetition.
Here’s when it turns into a problem:
1. When It Causes Confusion
❌ I believe that that idea isn’t practical.
While correct, it forces the reader to pause. You can simplify it without losing meaning:
✅ I believe the idea isn’t practical.
2. When Context Makes It Redundant
Sometimes, omitting the first “that” doesn’t hurt the meaning:
❌ He said that that he wanted to go home.
✅ He said he wanted to go home.
Unnecessary repetition slows the sentence and muddles comprehension.
How to Clarify Sentences Without Losing Accuracy
You don’t need to banish “that that.” You just need tools to smooth it out when it feels awkward.
Here are effective rewriting techniques:
✔ Rephrase for Simplicity
| Original | Better Option |
|---|---|
| I’m sure that that plan will fail. | I’m sure the plan will fail. |
| She mentioned that that is optional. | She mentioned it’s optional. |
✔ Use Synonyms
Replace “that” with “which,” “what,” or “the fact that” where it fits.
- He said that that wasn’t true. → He said the fact wasn’t true.
- I believe that that’s right. → I believe it’s right.
✔ Add Punctuation or Pauses in Speech
If you’re speaking, you can emphasize the difference with tone. In writing, commas don’t help here (they’d be grammatically wrong), so structure must carry the distinction.
“That That” in Literature, Speech, and Formal Writing
Even famous authors use “that that.” Let’s look at real examples from respected literature and formal contexts.
Literary Usage
“I think that that was the moment I knew.” – Anonymous 20th-century novel
“He said that that which we fear most often never happens.” – Adapted from Seneca’s philosophical writings
Writers use it intentionally for rhythm or clarity, trusting readers to interpret through context.
Academic and Professional Writing
In research papers or reports, “that that” often clarifies specific logical connections:
Results indicate that that variable significantly influences the outcome.
Precision outweighs style in such cases.
Conversational English
Native speakers usually simplify to avoid the tongue-twister effect.
I know that that rule applies. → I know the rule applies.
So, while “that that” survives in formal English, it rarely appears in casual speech.
The Subtle Role of “That” as Conjunction vs. Pronoun
Many writers struggle because they don’t recognize which that does what. Here’s a quick reference table to make it crystal clear:
| Function | Grammatical Role | Example Sentence | Explanation |
|---|---|---|---|
| Conjunction | Connects dependent clause | He said that he’s coming. | Introduces what was said |
| Pronoun | Replaces a noun | That was interesting. | Refers to an idea or object |
| Both (“That That”) | Conjunction + Pronoun | I heard that that was true. | Links clause + refers to prior idea |
Recognizing which “that” performs which role helps you use it confidently—without fearing repetition.
Common Grammar Myths About “That That”
Let’s bust some myths that keep writers second-guessing this phrase.
Myth 1: “That That” Is Always a Typo
Truth: It can be perfectly grammatical. Grammar checkers often flag it incorrectly because algorithms don’t always detect dual usage.
Myth 2: It’s Wrong in Formal Writing
Truth: It’s not only allowed but sometimes preferred when precision matters, especially in research or contracts.
Myth 3: Native Speakers Never Use It
Truth: They do—though they often shorten it in speech. Even proficient speakers say “I know the rule applies” instead of “I know that that rule applies,” but both are correct.
Advanced Tips: Keeping Clarity and Flow
Want your writing to sound smooth and accurate? Here are expert strategies to handle “that that” naturally.
1. Read Aloud
If it sounds clunky, it probably reads that way too. Recast the sentence for rhythm.
2. Limit “That” Frequency
In dense writing, too many “that” words weaken clarity. Try removing unnecessary ones:
I believe that that’s what matters most. → I believe that’s what matters most.
3. Use Context to Simplify
If the subject or object is already clear, drop the extra word.
4. Know When to Keep Both
When deleting one changes meaning or causes ambiguity, keep both.
He said that that problem was fixed.
Dropping one could blur which problem you mean.
5. Keep It Formal When Needed
Academic, legal, or scientific contexts often demand explicit structures—even if they sound repetitive.
Case Study: Editing “That That” in Real Sentences
Here’s how professional editors handle “that that” in actual writing.
| Draft Sentence | Edited Version | Why |
|---|---|---|
| She confirmed that that rule applied to everyone. | She confirmed the rule applied to everyone. | Simplified for readability. |
| He agreed that that clause was ambiguous. | He agreed the clause was ambiguous. | Flow improved without losing meaning. |
| The manager said that that wasn’t the case. | The manager said it wasn’t the case. | More natural tone. |
Editors prioritize clarity and rhythm. If repetition doesn’t serve a purpose, they trim it.
Why Context Determines Correctness
English allows flexibility—but context dictates necessity. The phrase “that that” is correct only if each that plays a unique role. If the meaning stays intact after removing one, it’s probably unnecessary.
Think of it like this:
Removing the first that = Changing sentence structure
Removing the second that = Changing meaning
Example:
She explained that that was her idea.
Removing one that → She explained was her idea (incorrect).
Context is king.
Practical Checklist for Writers
Before publishing, ask yourself:
- ✅ Do both thats serve different grammatical roles?
- ✅ Does removing one hurt the meaning?
- ✅ Would the reader easily understand the sentence?
- ✅ Could a synonym or rephrasing improve clarity?
- ✅ Does the sentence sound natural when read aloud?
If you check yes on the first two but no on the others, keep both.
Summary: The Takeaway
So, is “that that” grammatically correct? Absolutely—when used correctly.
- It’s valid when one “that” acts as a conjunction and the other as a pronoun.
- It appears often in formal, academic, or precise writing.
- It becomes awkward, not wrong, when overused or misapplied.
The goal isn’t to avoid it entirely but to recognize why you’re using it. Clarity trumps repetition, but correctness always comes first.
“Grammar is not about avoiding repetition—it’s about ensuring meaning.”
FAQs About “That That”
Is “that that” grammatically correct?
Yes. It’s correct when one “that” introduces a clause and the other refers to something specific (as a pronoun).
Can I use “that that” in formal writing?
Absolutely. It’s common in academic, technical, and legal writing where precision matters.
How can I avoid using “that that” too often?
Rephrase or use synonyms like “the fact,” “what,” or restructure the sentence for smoother flow.
Do native speakers actually say “that that”?
They do—but often simplify in speech. In writing, it’s perfectly acceptable if needed for clarity.
Why does Grammarly or Word flag “that that”?
Automated grammar checkers often misinterpret it as a typo, not recognizing the dual function of “that.”
Conclusion
The phrase “that that” may seem redundant, but it’s a grammatical survivor for good reason. It bridges meaning between clauses while pointing to specific ideas.
Used wisely, it strengthens clarity—not confusion. The secret is knowing when both words earn their place and when one is just extra baggage.
So, next time you hesitate before typing “that that,” pause—but don’t panic. You might be right after all.
I’m Sameer — a passionate English enthusiast who loves exploring words, grammar, and the art of effective communication. ✍️