topic How do I report adjusted cost basis from supplement form? in Investors & landlords

How do I report adjusted cost basis from supplement form?

Littlehuman — Mon, 09 Mar 2026 05:28:49 GMT

Hi,

I sold my vested company stock last year. This was my first time selling vested stock and I'm confused about how I need to report them.

I used Turbox tax's import feature to import transactions from etrade.com. I see 32 transactions with $0 cost basis. Reading responses from this forum, it looks like that's expected.

I just found out that there's also "Stock Plan Transactions Supplement" from from etrade.com and it shows an adjusted cost basis.

Should I enter those adjusted cost bases one by one for the imported 32 transactions or is there a way to import them and update existing transactions?

Re: How do I report adjusted cost basis from supplement form?

RaifH — Sun, 20 Feb 2022 20:11:41 GMT

Yes, you should adjust the cost bases of each transaction one by one. There is no way to update them as a batch, and your cost basis per share would be different if the sales were coming from different lots.

You can also report them by grouping them into long-term and short-term transactions and reporting the totals from each section rather than importing them. If you do this, you will need to include a pdf of your 1099-B with your return.

Re: How do I report adjusted cost basis from supplement form?

Littlehuman — Sun, 20 Feb 2022 20:46:20 GMT

Thank you so much.

Do I still need to attach 1099-B PDF when I adjust each transaction?

How should I attack my PDF? Turbo tax did not ask anything when I imported my transactions.

Re: How do I report adjusted cost basis from supplement form?

RaifH — Sun, 20 Feb 2022 21:12:09 GMT

If you only report the summary sales section, TurboTax will prompt you to attach the pdf since the IRS requires a record of each sale.

If you are recording each transaction separately and adjusting the entries, no pdf will need to be attached. The Schedule D that is part of your return will serve as the record for each sale.

Re: How do I report adjusted cost basis from supplement form?

dboeger1 — Thu, 31 Mar 2022 19:01:22 GMT

Thank you @RaifH for providing your answer. However, you did not explain the process for reporting the adjusted cost basis in TurboTax 2021. I vaguely remember that in prior years, I just manually entered the adjusted cost basis provided by E*Trade and everything worked out. However, in TT2021 (I'm using the Windows download product), regardless of whether or not I put in $0 or the adjusted amount for cost basis, the interview format eventually reaches a screen titled "Enter Vesting (or Release) Information" which asks for details related to sell-to-cover. This is confusing because when importing the RSU sales from E*Trade, it lists all individual sales, including the sell-to-cover ones. Intuitively, I can't imagine I'm supposed to put in the same information for both the original sell-to-cover sale and the eventual sale of the remaining shares in the lot, unless I'm misunderstanding something. How should I go about providing the correct adjusted cost basis for all sales?

Re: How do I report adjusted cost basis from supplement form?

GeorgeM777 — Thu, 07 Apr 2022 15:52:38 GMT

Yes, and to follow-up on the comments from @RaifH, TurboTax will ask about your sales and then it will ask about the shares sold to cover the tax withholding. You are moving through the screens correctly. Eventually, you should see a page which asks about the total shares vested, and also about the number of shares withheld to pay taxes. Also, when you are asked to enter the market price on the vesting date, enter the actual market price, not zero. Then continue through the rest of the screens.

@dboeger1