Only the portion of investment income that brings your modified AGI over the threshold for your filing status is subject to the additional 3.8% tax. $177 of NIIT implies that your modified AGI is only $4,658 over the threshold. That would imply that your modified AGI is roughly $204,658 if filing Single, $254,658 if Married Filing Jointly or $129,658 if Married Filing Separately.
