With the confusion over whether or not your employer was withholding enough tax on your behalf, or if your 2018 estimated payments should be based on your 2017 tax liability, or reflective of the new tax legislation, the IRS has decided to give some of us a break.
So long as you paid in 85% of your total tax liability for 2018, your penalty will be waived. For more information, please see IRS Notice 2019-11.