Based on the NIIT documentation, it is 3.8% of investment income, turbotax seems to get a smaller number and it is only based on 1099-INT and not 1099-DIV. Why is that?

[amyzheng1995]

Under Income, I see investments and savings total to be $5360. However the NIIT is 177, which is less than 3.8% of total. I am curious on how Turbotax is calculating this. Was there an unknown deduction or only 1099-INT is factored in?

[VolvoGirl]

Will this help?  See this IRS on the 3.8% tax on Net Investment Income

http://www.irs.gov/uac/Newsroom/Net-Investment-Income-Tax-FAQs

[amyzheng1995]

I did go through this document before and suspect TurboTax is under calculating the NIIT. I got 204 based on the numbers I have yet TurboTax is getting 177

[dmertz]

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.

[konstk1]

I'm seeing something similar. My TurboTax NIIT is calculated to be $42 lower than CashApp taxes. I don't have visibility into TurboTax 8960 so I don't know exactly what's different. The interest and dividends are the same between the two platforms.

[AmyC]

Here is the form and instructions, About Form 8960, Net Investment Income Tax Individuals, Estates, and Trusts

To view the full forms, in your return, you would need to pay for the software.

To see your forms:

• In desktop, switch to Forms Mode.
• For online, see How do I preview my TurboTax Online return before filing?

@konstk1 

[konstk1]

@AmyC This is not particularly helpful because I'm using TurboTax online, and I'm not paying for it until I know it's calculating everything correctly.

[codejunkie]

I'm seeing very similar behavior as well. I can't seem to reconcile the difference.

[konstk1]

I figured this out (at least compared to CashApp). It was actually CashApp's fault. They didn't automatically deduct line 9b (State, local, and foreign income tax). I had to calculate and enter it manually. TurbotTax did this automatically.

[bes825]

I see the same issue as reported, but I don't have any state/local/foreign taxes paid on my INT/DIV income. I still see the discrepancy.

[konstk1]

Unless your state has no income tax, you pay taxes on investment income when you file state. You need to calculate what that is and deduct it.

[bes825]

My sincere apologies; this is my first year filing 8960 (I'm not really sure why it never triggered in the past). I figured out my error: I wasn't accounting for my investment gains/losses (2023 line 5a). Since I had a capital gain loss on 1099-B, it subtracts from INT and DIV, and gets me to the exact calculation TurboTax reports. 

Thanks for the help! Sorry I co-opted the post (this probably deserved it's own topic)!