Republicans in Congress spent much of 2017 seeking to repeal and replace the Affordable Care Act. After repeated attempts failed, they celebrated a victory with the passage of the Tax Cuts and Jobs Act of 2017. While the tax bill left most of the ACA intact, it included the repeal of the ACA's individual shared responsibility penalty, the penalty imposed on individuals who fail to purchase qualified insurance coverage.
That means the so-called individual mandate remains in the ACA but, beginning in 2019, individuals will no longer face a financial penalty if they choose not to purchase health insurance.
