I forgot to input a 1099 form for tax year 2021

[AaronHxZ]

Hi, my name is Aaron I’m looking for advice because I received a CP 2000 form proposing a grossly huge number that I owe ($120,000) and then it shows that I had forgotten to report a 1099 form from Robinhood crypto brokerage that I used back in 2021. I found the form I need to show. I never made any significant gains throughout my transactions if anything, I believe I was at a loss. I’m just looking for advice whether I should amend the past tax return, or reply to the CP 2000 saying I disagree with a copy of the 2021 1099 form? Any help is appreciated Thankyou 

[fanfare]

you can't just forward a 1099-B to the IRS.

you will have to amend your tax return (Form 1040-X) to show on Form 8949  the cost basis  col(e) for your proceeds col(d) so that it is not all taxable

I would be replying in writing to the letter to tell the IRS you will be filing an amendment within the next three business days.

when filing 1040-X on paper,

Do not include your old 1040 nor your revised 1040 because the Form 1040-X reflects any changes there and becomes your new tax return.

@AaronHxZ 

[fanfare]

You did not say what the IRS told you to do.

Follow the instructions in the letter from the IRS.

It should tell you how to dispute.

@AaronHxZ