The IRS has now issued proposed regulations and revised answers to Frequently Asked Questions (“FAQs”) on the provision of the Affordable Care Act (“ACA”) imposing an additional 0.9% Medicare tax on wages in excess of specified thresholds.  Employers will want to familiarize themselves with this guidance, which will require that they withhold this additional Medicare tax from any employee’s “Medicare wages” in excess of $200,000 during a calendar year.