"Federal Refund" calculation

[joe-joe-joe]

I am in the middle of a tax bracket (example: 24%).

When I enter Interest income, let's say $100.  I would expect the "Federal Refund" counter box in the software to drop by $24.  24% of income addition via interest ($100).

That number is dropping by a much higher percentage than my tax bracket.  Why?

Is there additional tax applied to interest income beyond the tax bracket for higher tax brackets?

thanks

[MinhT1 · Accepted solution]

You may be liable for the 3.8% NIIT tax.