approximately about

"Their going to" is usually incorrect when you mean "they are going to." Use "they're going to" or "they are going to," and keep "their" for possession.

Quick answer

"Their going to" is wrong if you mean "they are going to." Use "they're" or "they are."

Their = possession (their car, their idea).
They're = contraction of they + are (they're going).
If you are unsure, write the full form: they are going to.

Core explanation

"Their" answers "whose?" It must be followed by a noun. If the following word is a verb (going, coming, doing), test by expanding to "they are." If the sentence still makes sense, use "they're" or "they are."

Their = possession (their plan).
They're = they are (they're arriving).
There = place (over there).

Real usage and tone

Pick the form by tone. "They're going to" fits speech, chats, and casual writing. "They are going to" sounds more formal or emphatic.

Formal/report: use they are going to.
Conversational: they're going to is natural.
Short/informal: use contractions like they'll when appropriate.

Examples: common wrong/right pairs to copy

If you see "their" before a verb, stop and replace it with "they are." If that reads correctly, change it.

Wrong: Their going to the meeting at nine.
Right: They're going to the meeting at nine.
Wrong: I can't believe their late again.
Right: I can't believe they're late again.
Wrong: Their planning to submit the report today.
Right: They're planning to submit the report today.
Casual - Wrong: Their coming over for dinner.
Right: They're coming over for dinner.
School - Wrong: Their going to grade the tests this afternoon.
Right: They're going to grade the tests this afternoon.
School - Wrong: Their going to present their findings in class.
Right: They're going to present their findings in class.
Work - Wrong: Their going to pick up the equipment after work.
Right: They're going to pick up the equipment after work.
Work - Wrong: Their going to send the invoice tonight.
Right: They're going to send the invoice tonight.
Wrong (possession): Their idea won the pitch. (Correct use of "their")
Right (contraction): They're going to pitch the idea themselves.

Rewrite help: 3 quick fixes and ready rewrites

Three-step fix: 1) Ask "Whose?" - if it answers whose, keep "their." 2) Replace "their" with "they are" - if it fits, use "they're" or "they are." 3) If you want brevity, consider "they'll."

Neutral rewrite: Wrong: "Their going to lead the presentation." → They're going to lead the presentation.
Formal rewrite: Wrong: "Their going to finish the audit by Friday." → They are going to finish the audit by Friday.
Short rewrite: Wrong: "Their going to review the code." → They'll review the code.
Casual rewrite: Wrong: "Their coming to the party." → They're coming to the party. Or: They'll come to the party.

Try your own sentence

Test the whole sentence by expanding "their" to "they are." Context usually makes the correct form obvious.

Memory trick: a tiny habit that works

Mnemonic: Ask "Whose?" If you can answer with a noun, use "their." If the sentence answers "What are they doing?", use "they're."

Habit: When you type "their" and a verb follows, stop and replace with "they are." If it reads well, change it to "they're."
Quick cue: Whose? = their. Are they? = they're.

Similar mistakes to watch for

The same quick checks fix other common confusions: your/you're, its/it's, and there/their/they're.

Your = possession; you're = you are. Example: Wrong: "Your going to love this." → You're going to love this.
Its = possession; it's = it is or it has. Example: Wrong: "Its been a long day." → It's been a long day.
There = place; their = possession; they're = they are. Example: Wrong: "There going to send it." → They're going to send it.

Hyphenation and contractions: what to avoid

Contractions use an apostrophe, not a hyphen. Don't remove the apostrophe or join the contraction to the next word.

Correct: they're going.
Incorrect: theyre going or they're-going.
Apostrophes show missing letters; hyphens link words (well-known), they do not form contractions.

Spacing, punctuation and a short grammar cheat-sheet

Contractions need an apostrophe and a space before the next word. Punctuation follows the contraction as usual.

Correct spacing: They're going to start soon.
Wrong spacing: They'regoing to start soon.
Cheat test: Replace with "they are." If it still makes sense, use "they're."

FAQ

Is "Their going to" ever correct?

Almost never. "Their" is correct only if it shows possession and is followed by a noun. If you mean "they are going to," write "they're" or "they are."

Which is safer to write if I'm unsure: "they're" or "they are"?

Write "they are" to be safe. It is always correct and avoids apostrophe mistakes; shorten it later if needed.

How can I stop making the mistake in fast chats?

Use the quick habit: whenever "their" precedes a verb, immediately expand to "they are." If it reads correctly, switch to "they're."

Will grammar checkers catch this error?

Most modern checkers flag "their" used as a contraction and suggest "they're." Learning the rule helps you catch errors the checker might miss.

Any one-line rule I can stick on my desk?

Whose? = their. Are they? = they're. Place? = there.

Quick next step

When you see "their" followed by a verb, pause and test it by expanding to "they are." If it fits, use "they're" or the full form "they are." Copy the three-line cheat-sheet and keep it handy until it feels automatic.