Additional Medicare Tax 2024 Threshold. Under the affordable care act, taxpayers who earn above a set income level (depending on filing status) pay 0.9% more into medicare on top of.  — the additional medicare tax is an extra 0.9% on earned income beyond a specific threshold limit.

 — the additional medicare tax 2024 rate is 0.9%. In 2024, the additional medicare tax remains unchanged at 0.9%.