I don't think a correction is necessary. Both parts of the sentence are already in the present tense. Plus, the use of "us" in the beginning of the sentence indicates a personal attachment.
I would have to say formal, mainly because I looked it up on google.
After his release from jail, a friend paid his taxes for him, Thoreau reflects on how his perceptions of his neighbors has changed. ... After his release from jail, a friend paid his taxes for him, Thoreau reflects on how his perceptions of his neighbors has changed.
