What is net investment income tax and form 8690? Never had to fill these out in the past but now it is required. Also you search the community option offered no info.

The net investment income tax is a 3.8% Medicare surtax on investment income.

If you have investment income and your modified adjusted gross income exceeds:

• $250,000 (married filing jointly),
• $125,000 (married filing separately),
• or $200,000 (all other filing statuses), 
• then you will most likely be subject to the 3.8% additional tax.

The form is used to calculate and report the 3.8% additional tax on investment income for the Affordable Care Act provisions that went into effect starting with the 2013 tax year.

See the following for additional information: 

• IRS https://www.irs.gov/uac/newsroom/net-investment-income-tax-faqs