Penalty relief may be available from IRS
Taxpayers who have filed and paid on time and have not been assessed any penalties for the past three years often qualify to have the penalty abated. See the First-Time Penalty Abatement page on IRS.gov. A taxpayer who does not qualify for the first-time penalty relief may still qualify for penalty relief if their failure to file or pay on time was due to reasonable cause and not due to willful neglect. Taxpayers should read the penalty notice and follow its instructions to request this relief.
The IRS also expanded the penalty waiver for those whose 2018 tax withholding and estimated tax payments fell short of their total tax liability for the year. The penalty will generally be waived for any taxpayer who paid at least 80 percent of their total tax liability during the year through federal income tax withholding, quarterly estimated tax payments or a combination of the two. The usual percentage threshold is 90 percent to avoid a penalty.
In addition to penalties, interest will be charged on any tax not paid by the regular April due date. For individual taxpayers it is the federal short-term interest rate plus 3 percentage points, currently 6 percent per year, compounded daily. Interest stops accruing as soon as the tax is paid in full. Interest cannot be abated.