Someone just asked this question, and the answer is “yes.”
Most of the time, at least.
When to use a comma —When you use “too” in the adverb sense of saying “also,” “likewise,” or “as well,” the word should always be set off from the rest of the sentence with commas.
I want to go, too.
I, too, want to go.
Too, I want to go.
The same usually goes for the words “also,” “likewise,” and “as well.” Here, though, you need to think about the “sound” of your sentence and normal usage practice in similar sentences. “Also” seems to vary in its usage. It is set off by commas at the beginning or end of a sentence, but not necessarily in the middle.
Also, Bill wants to go.
Bill also wants to go.
Bill wants to go, also.
In a related adverb use, sometimes “too” modifies a verb in a way that emphasizes opposition to a previous negative statement. You would also use a comma here. Ironically, though, you wouldn’t use a comma in the opposite case, where you were emphasizing opposition to a previous positive statement.
TOO (uses comma)
Bill doesn’t want to go.
He does, too!
NOT (doesn’t use comma)
Bill wants to go.
He does not!
When NOT to use a comma — Sometimes “too” is used as a “degree” adverb. In this case it doesn’t modify a verb but instead modifies an adjective or another adverb. In sentences like these, you would NOT set off the “too” with a comma.
The pan is too hot. (modifies the adjective “hot”)
The train is moving too slowly. (modifies the adverb “slowly”)
So, to summarize: if your “too” means “also,” use a comma. If your “too” means “very,” “excessively,” or “extremely,” do not use a comma.
COMMA: I want to go, too (also).
NO COMMA: I arrived too (excessively) late to catch the train
I hope this is helpful!