Grammar rule

Commas after openers and before and, but, so

Put a comma after an opening phrase, and before and, but or so when they join two sentences.

Updated October 29, 2026

The rule

An introductory word, phrase or clause (However, After the game, When the bell rang) is followed by a comma.

When and, but, or, so, for, nor or yet joins two complete sentences, put a comma before it. When it joins two verbs that share one subject, use no comma: "She ran and jumped."

Examples

  • After the storm passed we walked to the beach.After the storm passed, we walked to the beach.
  • He opened the door, and walked in.He opened the door and walked in.

Quick test: Check whether a new subject follows "and". If it does, use a comma; if it doesn't, leave it out.

Try it: find the mistake

The mistake in each sentence is highlighted. Say the fix out loud, then open the answer.

After lunch we played tag.

After lunch, we played tag.

Put a comma after an opening phrase like "After lunch".

Yes I would like some juice.

Yes, I would like some juice.

Put a comma after an opening word like yes, no or well.

I wanted to go to the concert but I had homework.

I wanted to go to the concert, but I had homework.

But joins two complete sentences here, so it needs a comma before it.

She grabbed her keys, and ran out the door.

She grabbed her keys and ran out the door.

The second part has no subject ("ran out the door"), so no comma before and.

Play today's Grammar Fix, free

Where this rule is tested

  • The CLT's Grammar/Writing section and the SAT's Reading and Writing section both test it, usually as "which choice is correct" with four versions of a sentence.
  • In the Daily Grammar Fix, it comes up in sentences for grades 4 to 6, grades 7 to 9 and grades 10 to 12.

Questions people ask

What is the rule for commas after openers and before and, but, so?

Put a comma after an opening phrase, and before and, but or so when they join two sentences. An introductory word, phrase or clause (However, After the game, When the bell rang) is followed by a comma.

How can I check my commas after openers and before and, but, so quickly?

Check whether a new subject follows "and". If it does, use a comma; if it doesn't, leave it out.

Where can I practice this for free?

In Owl Test Prep's Daily Grammar Fix: one sentence a day for everyone, plus practice sets of five on this rule. It is free, with no account.

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