For a long time, correct punctuation dictated using a comma before the word “too”. Not anymore. According to the industry standard manual of style, The Chicago Manual of Style, 17th Edition, Section 6.52, a comma is no longer necessary. In fact, before the adverbs “too” and “either” the comma is no longer needed when the adverb is at the end of the sentence. If “too” is in the middle of the sentence or clause, the comma makes it easier to read and understand.
Jan likes caramel apples; her brother does too.
He, too, liked caramel apples.
I never got that memo from the Chicago Manual of Style. I use that comma before the word too all the time. I have a feeling I’m going to learn lots from this section of your web site. I might ignore some of it, but it will be nice to know that I’m doing it on purpose and not because of ignorance. 😉