It depends on what type of settlement it was and how the settlement funds were categorized. For example, settlement funds rewarded for lost wages are taxable and settlement funds rewarded for a personal injury are usually not. Also, if the funds you received are considered taxable income, then you will receive a tax form. Most settlements are reported on form 1099's. I would wait until after February 15, 2018, to assume that ones not coming. It could still be in transit.
Here's an informative website that relates to class action lawsuit settlements.
https://www.classaction.org/blog/are-class-action-lawsuit-settlements-taxable
Please view the following IRS page, as it lists the taxability of some common types of lawsuit settlement rewards.
https://www.irs.gov/pub/irs-pdf/p4345.pdf
