Is class action settlement taxable and what year?

Received settlement check of $31.77 in Dec of 2017 for a class action lawsuit I didn't know I was part of. It was an antitrust litigation settlement. A retail store was found to overcharge for certain products and I am assuming my purchases were included when the store turned over it's records. Cashed the check in Mar 2018 after finding out what it was. Is this taxable? In 2017 or 2018?

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