form 2210 schedule AI, NIIT

user17705283360 · ‎February 08, 2026

I'm using the desktop version of TurboTax Deluxe, married filling jointly. The annualized income for the 2nd annualize period (form 2210 schedule AI line 3b) is over $250,000. The annualized income for the other 3 periods is less than $250,000. Do owe NIIT (Net Investment Income Tax) for this during the 2nd period? TurboTax isn't automatically adding it to the tax due on form 2210 schedule AI line 14b. I can manually enter it on form 2210 schedule AI line 16b, but then TurboTax says there is an error and says "Line 16 should be blank."

Does this mean I don't owe NIIT for the for the 2nd period even though the annualized income exceeded $250,000 for that period? If I do owe NIIT (for just the 2nd period), what is the proper method getting it added when using the annualized method?

dmertz

"The annualized income for the 2nd annualize period (form 2210 schedule AI line 3b) is over $250,000. The annualized income for the other 3 periods is less than $250,000."

If you are referring to gross income, you are determining the income per period incorrectly. Each of the four periods begins on January 1, so each subsequent period includes the income shown for the previous period. This means the income for each subsequent period has to be at least as much as the previous period. In other words, each period shows gross year-to-date income, where the date is the ending date of the period.

The only way that you could have NIIT apply to period (b) and not to periods (c) and (d) is if you had substantial deductions added in periods (c) and (d) that are less that the income added for those periods.

baldietax

I was looking at this and the 2210 instructions don't specify anything about how to handle NIIT variations other than the comment on the form about including NIIT here. I see what you are saying - TT doesn't do the NIIT calculation automatically by quarter, but allows Line 16 to be adjusted if there was a value for the year as tho you are apportioning the year-end amount over the quarters like income; however doesn't handle a case where you are under NIIT for the year but jump above it for interim quarters (assuming it needs to be handled - maybe either NIIT applies to the entire year or it doesn't).

@dmertz @Mike9241 @DoninGA @VolvoGirl any thoughts?