Late 1099-B Filing - Form 1040X and 8453-OL, include 1099-B?

[ProphestPriestAndKing]

Long story short, I was filing my 2025 taxes only come to realize I did not file 1099-B in my 2024 tax return (out of ignorance, only entered 1099-DIV and 1099-INT at the top of brokerage document). To make right, I launched TurboTax 2024,  opened my 2024 tax return that I successfully e-filed to both IRS and Franchise Tax Board last year. I selected to Amend, and entered summarized 1099-B (no individual sales details). Afterwards, it gave me results on what I owe to IRS and Franchise Tax Board. At the end of the process, I tried e-filing and unsurprisingly it didn't let me since filing for 2024 is closed. I then elected to print the PDF document and noticed Form 8453-OL was generated.

My question is, should I include a copy of my 1099-B detailed transaction from the brokerage in my amended filing to both the IRS and Franchise Tax Board? There's no instructions to do so within the TurboTax generated documents and had understood this is needed. 

As an added note, I also will submit Form 843 to request abatement as recommended by IRS agent via phone, please advise if it is recommended otherwise.

[ReneV4]

Yes. You should include a copy of your Form 1099-B to both Federal and State.

Because you summarized, the IRS and the California Franchise Tax Board (FTB) need the supporting data to match your numbers.

Note: You can just print the summarized pages and the detailed transaction pages from your brokerage 1099-B and staple them to the back of your amended return.

Yes. It is recommended that you submit Form 843. If you have had a clean record for the three years prior to 2024, the IRS will almost always wipe the "Failure to Pay" or "Failure to File" penalties for a first-time oversight.

However, do not file Form 843 with your amendment. Wait until the IRS processes your amendment and sends you a bill (notice) for the interest and penalties.

because the IRS systems need to "charge" the penalty before they can "abate" it.

Once you get that bill, you can often just call the IRS and ask for a "First-Time Abatement" over the phone, which is much faster than mailing Form 843.

Summary checklist for mailing:

• Federal: Send Form 1040-X + a copy of your 1099-B + any changed schedules (like Schedule D)
• State: Send Form 540-X + a copy of your 1099-B
• Payment: If you owe money, include a check or pay online via the IRS/FTB websites. Paying immediately stops interest from growing
• Tracking: Send both via Certified Mail with a return receipt. This is your only proof that you met the deadline if the mail gets lost

[ProphestPriestAndKing]

Thank you, a few follow-up questions.

1. TurboTax instructions said to sign 8453-OL, but then on the top of 8453-OL it says "do not mail this form to the FTB", so do I sign and mail it or do I not?

2. TurboTax instructions said to sign and mail Form 3582, I only see 3582X in the amended return. I paid FTB online already, should I still include 3582X or should I just print online payment confirmation?

3. I also see Form 540 included but not 540X specifically, I just want to make sure I am submitting the right forms. TurboTax also included 1040X, 1040, and other expense forms as part of the print packet. Do I mail all of these in as compiled by TurboTax or just 540 as you first instructed?

4. I received 1099-G for tax year 2024 from California FTB. Since my amended return requires me to send money back, will I get a revised 1099-G from FTB showing a reduced amount for me to submit in my 2025 taxes (and if so, presumably I should not file my 2025 taxes until I get it?)

5. The federal 1040-X printout also included the original 1040 and other forms, do I include those (and sign them)?

Thank you.

[ThomasM125]

You do need to file the Form 540X to amend your California return. You will not get a revised Form 1099-G from California for 2025. Since your refund is not corrected until 2025, you will treat the refund received in 2025 as being correct, since you report income on a cash basis on your tax return. The state tax you pay back in 2025 will be accounted for on that tax return as state taxes paid in. You will file the 2025 tax return in 2026.