1099B for foreign stock sale received after filing

[benefitssteve]

I received a 1099B from a UK based brokerage for foreign stock sales after I had filed. I originally reported the income as no 1099 received. The 1099 I received used a currency conversion rate based on the US Treasury 12/31 rate. In filing, I used the actual rate the broker reported to me when they converted the proceeds from UK to US currency and wired the proceeds to my US account. There is now a discrepancy of $2050 approx due to the different coversion rates between the number I reported as proceeds and the number on the 1099. I believe I should file a 1040X to report the 1099B and reconcile the 1099B gross proceeds number to the actual funds I received based on the actual currency conversion rate used. My question is how to actually do this? I reported the original transaction as 16 sales because there were different acquistion dates - there was only one sale. All acquistion dates were older than one year so all long term. Can I do this as summary in one line or should I modify each line? Other steps I should take? I'm in California should I also file a state amended return. I don't believe this changes my actual income at all but I assume this could trigger a matching error when the post filing 1099 hits the IRS computers. Thanks in advance for any advice.

[ReneV4 · Accepted solution]

Yes and yes. You should file Form 1040X, as well as an amended California return to amend your prior year returns and properly report the discrepancy. 

If you used TurboTax last year, you can locate your prior year documents and returns by scrolling to the bottom of your Tax Home screen.

Since they were all long-term, you will not need to re-enter all of the sales. You can simply input the amount of the discrepancy when you are in the Investment Income section in the Federal Wages & Income category.

Here are the steps within TurboTax:

1. Open the tax year you need to change
2. Start the Federal Amendment first. Navigate to Wages & Income, Investment Income, Stocks, Cryptocurrency, Mutual Funds, Other
3. Edit the existing entry 
4. Enter the correct Form 1099-B information. TurboTax will compare this to what you did previously and generate the Form 1040-X automatically.
5. Review the State Section. After finishing Federal, go to the State tab to ensure the California amendment is triggered.

Note that you will need to mail these documents along with your amended returns:

Federal:

1. Form 1040-X: The main amendment form, signed and dated.
2. Corrected Forms/Schedules: Updated Schedule D and Form 8949
3. Form 1099-B: Highly recommended to include a copy of the new Form 1099-B for quick verification by IRS
4. Payment: Since the new Form 1099-B shows that you owe more tax, include a check or money order payable to "United States Treasury." Write your SSN and "2025 Form 1040-X" on the memo line.

California:

1. Form 540 (Amended): In California, you typically file a new Form 540 with the "Amended" box checked at the top
2. Schedule X: This is the California-specific form used to explain the changes
3. Copy of Federal 1040-X: California requires a complete copy of your federal amended return to be attached to your state amendment
4. Form 1099-B: Include a copy for the State

[benefitssteve]

thank you for the information. Does it make a difference that this is for the 2025 tax year - I was efficient and filed early this year😀. I'm hoping it means I can do some of it online. The UK broker in question had never sent 1099's in the past but they did this year. Given that it is for 2025 do you have any advice as to timing? Wait for the current season to end or get the adjustment in ASAP - IRS has already processed my return as has the State.

Thanks Again!

[JamesG1]

If the amended income tax returns will generate a balance due to the tax authorities, there is a benefit to amending earlier rather than later.  

I would amend prior to the April 15 filing deadlines.

@benefitssteve