Theirs or There's: Which One Do You Need?

Apostrophes cause more trouble in English than any other mark, and this pair concentrates the whole problem into two short words. Writers know that an apostrophe has something to do with possession, see that theirs expresses possession, and reach for one. The logic is sound and the conclusion is wrong, because possessive pronouns are the one family that English deliberately exempts. Meanwhile there's, which has nothing to do with ownership at all, keeps its apostrophe for an entirely different reason. Sorting out which mark belongs where takes one rule and two quick tests, and it settles a large group of commonly confused words at the same time.

Which One Do You Need?

Theirs is a possessive pronoun. It means belonging to them and it stands alone, without a noun after it: "the corner office is theirs," "ours is smaller than theirs," "theirs was the only objection." No apostrophe, ever.

There's is a contraction of there is, or occasionally there has: "there's a problem with the invoice," "there's been a change of plan." The apostrophe is holding the place of the letters that were removed.

Two further forms turn up in drafts, and neither is correct. Their's does not exist in any variety of English. Theres, with no apostrophe at all, is not a word either; if you mean there is, the apostrophe is compulsory.

The Rule: Possessive Pronouns Refuse Apostrophes

The whole difficulty dissolves once you see that English uses the apostrophe for exactly two jobs, and possession by a pronoun is not one of them.

The apostrophe marks a contraction, standing in for removed letters: don't, we'll, there's. Or it marks a possessive noun: the dog's bowl, Marta's coat, the students' union.

Possessive pronouns are a separate class, and they are already possessive in their own form. Line them up and the pattern is unmistakable:

Pronoun	Possessive form	Apostrophe?
he	his	no
she	hers	no
it	its	no
we	ours	no
you	yours	no
they	theirs	no

Nobody is tempted to write hi's, because his obviously does not need help to mean what it means. Hers, ours, yours, and theirs work identically. They are not nouns wearing a possessive ending; they are complete words whose entire job is to signal ownership.

This is also why its and it's trip up so many writers in the same way. Its is the possessive pronoun, so no apostrophe. It's is the contraction of it is. The rule is a single one, applied twice.

Where the Error Comes From

The main driver is a half-learned rule. Most people absorb "apostrophe equals possession" from the noun cases they meet first, the cat's tail, my brother's car, and then extend it to any word that expresses ownership. The extension feels rigorous, which is exactly why it survives proofreading: the writer believes they are applying a rule rather than guessing.

Homophony supplies the second push. Theirs and there's are pronounced identically in ordinary speech, so the ear provides no correction, and a writer choosing between them is working from spelling knowledge alone.

A third pressure is the crowd of similar words. English asks writers to keep their, there, they're, theirs, and there's apart, five forms built from two sounds. Having navigated the first three correctly, most people are running low on attention by the time the fourth and fifth arrive.

Theirs and There's in Real Sentences

Correct:

• The decision was theirs to make.
• There's no milk left in the fridge.
• Our garden is bigger, but theirs gets more sun.
• There's been a delay on the northbound line.

Incorrect, with fixes:

• The mistake was their's. → The mistake was theirs.
• Theirs a problem with the booking. → There's a problem with the booking.
• Theres nothing we can do. → There's nothing we can do.
• Is this seat their's or ours? → Is this seat theirs or ours?

The second example is the one worth studying, because it shows the error running in the opposite direction: a writer who has learned that theirs takes no apostrophe sometimes strips the apostrophe from there's as well. The two words follow different rules and have to be decided separately.

Theirs vs There's: Side by Side

Aspect	Theirs	There's
What it is	possessive pronoun	contraction
Means	belonging to them	there is / there has
Apostrophe	never	always
Expands to	nothing	there is, there has
Same family as	his, hers, ours, yours	it's, we're, don't
Wrong forms	their's	theres

The "expands to" row is the practical one. A contraction can always be unpacked into the words it replaced; a possessive pronoun cannot, because nothing was ever removed from it.

Two Tests That Settle It

The expansion test. Read the sentence with there is substituted in. "There is a problem with the invoice" works, so there's is correct. "The corner office is there is" collapses immediately, so the word you want is theirs.

The his test. Ask whether you would write an apostrophe in his. You would not, and theirs belongs to the same closed family of possessive pronouns, so it cannot take one either. This test also rescues hers, ours, yours, and its in one move.

Between them the two checks cover every case. If the expansion works, use the apostrophe; if the word is doing the same job as his, leave it off.

A Memory Hook That Sticks

Hold onto one sentence: an apostrophe is a hole, not a badge. It marks where letters have been taken out, or where a noun has been given an ending. It is never a decoration awarded to a word for expressing ownership. There's has a hole in it where i used to be. Theirs has nothing missing, so there is nothing for an apostrophe to stand in for.

If you prefer a shorter cue, remember that theirs keeps the I of their, while there's keeps the ere of there. Spelling and meaning travel together: the possessive stays with the possessive family, and the contraction stays with the place word.

Related Spelling Mixups

Theirs vs there's is one corner of a larger tangle. Its closest neighbour is their or thier, which handles the letter order of the base possessive and sorts out their, there, and they're along the way; read that one first and this pair becomes much easier. From the grammar side, plural vs possessive sets out the underlying apostrophe rule in full, covering when a noun takes 's, when it takes s', and when it takes nothing at all. Together the three cover almost every apostrophe decision an ordinary writer has to make. Two further pairs test the same instinct from other directions: discrete vs discreet, where both spellings are real words and only the meaning decides, and seak vs seek, where spelling by ear produces a word that does not exist at all.

Conclusion

Theirs never takes an apostrophe and there's always does, because they are doing unrelated jobs. Theirs is a possessive pronoun in the same closed family as his, hers, ours, and yours, none of which needs a mark to signal ownership they already carry in their own form. There's is a contraction, and its apostrophe is simply standing where the letters of is or has used to be. That leaves their's and bare theres as errors with no legitimate use anywhere. When you are unsure, expand the word to there is and see whether the sentence survives, or ask whether you would put an apostrophe in his. For more pairs where one punctuation mark decides everything, browse the full set of commonly confused words.