on-going (ongoing)

Short answer: Use ongoing (one word, no hyphen) to mean "continuing" or "in progress."

Below: why the hyphen appears, when two words are ever correct, and plenty of copy-paste wrong/right pairs and rewrites for work, school, and casual contexts.

Quick answer

ongoing = correct adjective for something continuing or in progress. Avoid on-going and on going for that meaning. If a straight replacement feels awkward, rewrite the sentence (examples below).

ongoing = correct (e.g., ongoing project).
on-going = nonstandard or outdated; don't use in modern writing.
on going = almost always wrong for "continuing"; only use two words if the words are grammatically separate.

Core grammar: why ongoing is one word

Ongoing is a closed compound adjective that has become standard. Use it before a noun (ongoing costs) or after a verb (the review is ongoing).

Attributive: ongoing project, ongoing costs.
Predicate: The investigation is ongoing.
Incorrect forms: on-going project, on going project (for "continuing").

Correct: The ongoing investigation will take weeks.
Correct: Ongoing costs must be budgeted each month.

Hyphen history and why you still see on-going

Hyphens were once used to ease reading during spelling transitions. As usage solidified, many compounds lost their hyphens - ongoing followed that pattern.

You may encounter on-going in older texts, scans, or unedited drafts; modern style guides list ongoing.
If quoting older sources, modernize to ongoing when you summarize or edit for contemporary usage.

Spacing: when "on going" (two words) is different

"On going" is only correct when on is a separate preposition or adverb and not part of the adjective meaning "continuing." Those cases are rare and usually clearer if rewritten.

Use ongoing for continuity: ongoing discussion, ongoing support.
Only use two words when the meaning is literally "on" + "going" and the grammar requires separation-prefer to rewrite to avoid confusion.

Wrong: The on going repairs will take months.
Right: The ongoing repairs will take months.
Literal but rare: He left him on, going about his business. (awkward; rewrite)

Short grammar checklist (fast fixes)

Spot a hyphen or split form? Try these quick steps.

Step 1: Replace with ongoing.
Step 2: Read the sentence aloud. If it still sounds clumsy, rewrite.
Step 3: In casual speech, prefer "still going" or "still happening."

Quick rewrite: Original: We need an on-going report. Fix: We need an ongoing report. If clunky: Please send a status report every week.

Real usage and tone: formal, neutral, casual

ongoing fits most registers: formal reports, academic prose, journalism, and everyday notes. For speech or texts, conversational phrasing often sounds more natural.

Formal: The audit is ongoing and will conclude next month.
Neutral: Ongoing assessment includes quizzes and projects.
Casual: The party's still going - come by when you can. (use "still going" in chat)

Work: The audit is ongoing and will conclude next month.
School: Ongoing assessment includes both quizzes and projects.
Casual: The party's still going - come when you can.

Try your own sentence

Test the whole sentence rather than the phrase alone. Context usually makes the right choice clear.

Examples: common wrong/right pairs you can copy

Replace the wrong forms below with the corresponding correct versions. Grouped by context for quick adaptation.

Work - Wrong: The on-going negotiations will resume Monday.
Work - Right: The ongoing negotiations will resume Monday.
Work - Wrong: Please attach an on-going status summary.
Work - Right: Please attach an ongoing status summary.
Work - Wrong: We have several on-going projects to prioritize.
Work - Right: We have several ongoing projects to prioritize.
School - Wrong: There's an on-going debate in the seminar.
School - Right: There's an ongoing debate in the seminar.
School - Wrong: On-going assessments will affect grades.
School - Right: Ongoing assessments will affect grades.
School - Wrong: The on-going research requires consent forms.
School - Right: The ongoing research requires consent forms.
Casual - Wrong: Sorry, I have an on-going issue with my phone.
Casual - Right: Sorry, I have an ongoing issue with my phone.
Casual - Wrong: There's an on-going sale at the store.
Casual - Right: There's an ongoing sale at the store.
Casual - Wrong: My on-going allergy is horrible this week.
Casual - Right: My ongoing allergy is horrible this week.

How to fix your sentence: quick rewrites (copy-paste)

If a straight swap still sounds awkward, these rewrites keep tone and clarity.

Original: The on-going debate continued throughout the night.
Rewrite: The debate continued throughout the night.
Original: She has an on-going problem with deliveries.
Rewrite: She continues to have problems with deliveries. / She has an ongoing delivery problem.
Original: We need an on-going plan for maintenance.
Rewrite: We need a continuing maintenance plan. / Simpler: We need a maintenance plan.
Original (casual): Sorry, I'm in an on-going meeting.Rewrite (casual): Sorry, I'm still in a meeting.
Original (formal): Please send an on-going status report.Rewrite (formal): Please send a weekly status report on progress.

Memory trick and one-line style rule

Mnemonic: Ongoing = one continuous word for a continuous action.

One-line rule: When you mean "continuing" or "in progress," use ongoing; if it feels awkward, rewrite rather than hyphenate.

Think "one motion = one word" to recall ongoing.
If unsure, check a current dictionary or style guide - ongoing is standard.

Similar mistakes to watch for

Writers who split or hyphenate ongoing often miswrite other compounds. Common traps and quick fixes:

everyday (ordinary) vs every day (each day)
altogether (completely) vs all together (in a group)
into (preposition) vs in to (different construction)

Wrong: He eats everyday.
Right: He eats every day.
Wrong: They are all-together in agreement.
Right: They are all together in agreement.
Wrong: She poured the sugar in to the bowl.
Right: She poured the sugar into the bowl.

FAQ

Is on-going correct English?

No. On-going with a hyphen is considered nonstandard today. Use ongoing.

Should I hyphenate ongoing in a formal report?

No. Use ongoing (no hyphen). If the sentence reads poorly, rewrite instead.

Is "on going" (two words) ever correct?

Only when on and going are separate grammatical pieces with a different meaning. Those cases are rare and usually clearer if rewritten.

How do I fix "an on-going problem"?

Replace with "an ongoing problem." Alternatives for emphasis: "a continuing problem" or "the problem continues."

My spell-check suggests "on-going" - should I accept it?

No. Spell-checkers can be inconsistent. Prefer ongoing and consult a current dictionary or style guide if unsure.

Want a second pair of eyes?

Paste your sentence into a grammar tool or swap in ongoing, then read aloud. If it still sounds off, use one of the short rewrites above - small edits usually fix the problem quickly.