Does switch from Standard Deduction to Itemized Deduction effect Net Investment Income Tax

[niks_sabharwal]

In turbotax, My Net Investment Income Tax is changing if I switch between Standard Deduction and Itemized deduction . For itemized deduction it is getting reduced by 400$. So overall tax bill is reduced by 400$

Switching from the standard deduction to itemized deductions should not directly affect the calculation of the NIIT, as the tax is based on MAGI and net investment income, not the taxable income after deductions.

 is this a software bug on turbo tax?

Looks like exactly $10K are getting reduced from Total investment income which is resulting in 380$ reduction

[rjs]

I don't have a complete answer for you. I'm not very familiar with NIIT. But the IRS instructions for Form 8960 line 9a say to enter investment interest expense "deducted on Schedule A." Could that be what's making the difference? Do you have a deduction for investment interest? Take a look at line 9a with the two different types of deductions.

If that doesn't explain it, compare the two versions of Form 8960 line by line, with the two different types of deductions, and see what the differences are.