So do i or So am i: Which Is Correct?

Updated 2026-10-03 · Which One Is Correct editorial team

Quick answer: Both forms are correct, but they serve different grammatical purposes. Use so do i when agreeing with an action verb. Use so am i when agreeing with the verb to be. The choice depends entirely on the main verb used in the first statement.

The Short Answer

You must match the auxiliary verb from the previous statement exactly. If the person used an action verb, use so do i. If they used the verb to be, use so am i.

People often mix these up because both phrases signal agreement at the end of a conversation. The confusion stems from forgetting that English requires the helping verb to mirror the original tense and type.

Side-by-Side Comparison

Form	Status	Use it when
so do i	Correct	The original statement uses an action verb
so am i	Correct	The original statement uses the verb to be
so i do	Incorrect	Never use this word order for agreement
so i am	Incorrect	Never use this word order for agreement

Correct Example Sentences

She loves jazz music, and so do i.
He is a talented painter, and so am i.
They finished the project early, and so did i.
You are welcome to join us, and so am i.
My brother plays the guitar, and so do i.
The cake was delicious, and so was i not.
We enjoy hiking trails, and so do i.
She is happy with the result, and so am i.
They arrived before noon, and so did i.
You are correct about the facts, and so am i.

Common Mistakes and Fixes

She runs fast, and so am i.: She runs fast, and so do i.
He is tired, and so do i.: He is tired, and so am i.
They like pizza, so i do.: They like pizza, and so do i.
We are excited, so i am.: We are excited, and so am i.
You work hard, and so is i.: You work hard, and so do i.
It was cold, and so am i.: It was cold, and so was i.

A Quick Test You Can Use

Look at the main verb in the first sentence. If it describes an action like run, eat, or think, use so do i. If it describes a state of being like happy, tall, or here, use so am i. Always match the helper verb to keep your grammar consistent.

Related Word Pairs

Me vs I: Use me as an object and i as a subject.
Who vs Whom: Use who for subjects and whom for objects.
Its vs It's: Use its for possession and it's for it is.
Your vs You're: Use your for ownership and you're for you are.
Their vs There: Use their for possession and there for place.

More Example Sentences

Sarah can swim across the lake, and so can I.
The children enjoyed the magic show, and so did I.
You are invited to the gala, and so am I.
My neighbor bakes sourdough bread, and so do I.
He has visited Paris three times, and so have I.
They are planning a road trip, and so are we.
The professor understands quantum physics, and so do I.
She is eligible for the scholarship, and so am I.
My friends prefer coffee over tea, and so do I.
You were present at the meeting, and so was I.

Quick Practice

My sister speaks French, and so I.

He is a certified chef, and so am .

They have already left, and so we.

have

You are tired from work, and so am .

The dog loves treats, and so I.

She will attend the concert, and so will .

Frequently Asked Questions

Can I use so do i with the verb to be?

No, you cannot. If the original sentence uses the verb to be, you must use so am i, so is he, or so are they to maintain proper grammatical agreement.

Is so am i formal or informal?

Both phrases are standard English. They are appropriate for everyday conversation, professional emails, and academic writing. The formality depends on the context of the surrounding sentence, not the phrase itself.

Why do people say so do i when they should say so am i?

This is a common error caused by habit. Speakers often default to so do i because it is used more frequently with action verbs, leading them to misapply it to state-of-being sentences.

Do I need a comma before and so do i?

Yes, usually. When joining two independent clauses with a conjunction like and, place a comma before the conjunction. This punctuation rule applies to both so do i and so am i.