For 2016 coverage, you could go silent on your tax returns regarding health coverage. For 2017 and 2018 coverage, going silent isn’t an option.
In general that means if you had health coverage, then you should attest to it, and if you didn’t then you should attest to that on your 1040.
This is different than with 2016 plans where confusion over the ACA and Trump led to the IRS letting people simply refrain from answering the question.
This is relevant for this tax season, however moving forward the fee for not having coverage is reduced to zero in most states. That means there is no fine attached to answering no to the health insurance question in future tax years in regards to plans held in 2019 and beyond.