8661 / Can a taxpayer make estimated tax payments to cover the additional Medicare tax liability?

Although the additional Medicare tax is a separate tax, the IRS considers it to be part of the taxpayer’s overall tax liability. So, if the taxpayer’s withholdings are not sufficient to cover the entire tax liability, there may be a penalty imposed on the failure to make an estimated tax payment. For that reason, it may benefit a taxpayer who does not increase the amount withheld by the employer to make estimated payments to cover any shortfall.¹

1. IRS Q&A on the Additional Medicare Tax, available at: http://www.irs.gov/Businesses/Small-Businesses-&-Self-Employed/Questions-and-Answers-for-the-Additional-Medicare-Tax (last accessed September 23, 2025).