Help in validating 1099-B capital gains tax being calculated

Forum|Forum|11 months ago
April 14, 2025
1 reply
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I sold some stock in 2024 which triggered 1099-B. I am entering that in TurboTax and have some questions as the tax due is significantly larger than I calculated during sale.

First I completed all my taxes before entering 1099-B in TT and I see my taxable income 1040 line 15 is 506,9xx (~500k)

The I entered the 1099-B in TT and it calculated the tax which differs from my calculation.

2024 long-term capital gains tax on $84,656.92.

Long-Term Capital Gains Tax (15%) $12,698.54

Net Investment Income Tax (3.8%) $3,217.36

Total Capital Gains Taxes $15,915.90

I also had some short term gains, and short-term capital gain on $443.61

Income Tax (35%) $155.26

NIIT (3.8%) $16.86

Total tax $172.12

In Summary

Long-Term Gain on $84,656.92 = $15,915.90

Short-Term Gain on $443.61 = $172.12

Total tax $16,088.02.

But turbotax is calculating 413 dollars more.

DianeW777

It depends. The net investment income tax (NIIT) kicks in when the investment income exceeds a certain limit.

What is Form 8960: NIIT (Click to review for more details)
- If you file a joint return or use the Qualifying Surviving Spouse status, your MAGI (as of publication date) has to be more than $250,000
- If you're married but file separately, your MAGI has to be more than $125,000
- Single and Head of Household filers can report an MAGI of $200,000 or less

As long as you entered the proceeds and cost basis then TurboTax calculated the tax correctly. It's best to review your tax return before you file it.

You have access to all forms when you choose to print your return in TurboTax Online/Mobile. However you are required to pay before printing, but do not have to file until you are ready.

Can I print a copy of my return in TurboTax Online before filing?

If you are using TurboTax Desktop you can switch to Forms and review all forms and worksheets.

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frostily0495Author

@DianeW777 Thanks. Which form I can look at to see the tax calculation on the long term and short term capital gain in forms view. I see Form 8949 which only has all sales listed which I entered and total profit.

Where can I see the tax amount TT is calculated and the maths for it?