The Tax Cuts and Jobs Act of 2017 repealed the shared responsibility payment, which is a penalty for not having minimum essential health coverage (and not being exempt from this requirement). But the repeal doesn’t impact 2018; it only provides relief after 2018.
A 12-month period ending on the last day of any month other than December. Partnerships, S corporations, and personal service corporations are limited in their choice of fiscal years and face special restrictions.