For each taxable year, the MAGI, after being reduced by a fixed threshold, is compared to NII.

FORBES: What the New 3.8% Medicare Surtax Means for You And Your Investments

"This crash began back when refining problems around the country were being fixed, one after the other, at the same time that our seasonal gasoline demand was shrinking, " she said.

CNN: U.S. gas prices 'crash'