Question: Form 1099-B - Missing Cost Basis not provided by broker

[codewarrior_777]

I'm trying to fill out the personal income section, my Form 1099-B specifically, but for one section of it the Cost Basis was not provided by the broker.

I received the 1099-B because I received money from a custodial account that my parents set up for me when I was young and decided to give it to me at this point. It was a mutual fund and was converted to another mutual fund account in my name. 

I've been going back and forth with the broker and TurboTax support, but I'm still not sure what to put in the section 1e - Cost or Other Basis for the info that is missing. 

One TurboTax support person told me that I should not leave it blank or 0 because then I would have to pay taxes on the full amount received. I believe he told me to calculate what the shares were on the day that I received and put that number in the Cost Basis box. 

There are three other sections  (4 total) that are filled out completely and I'm not sure how they are calculating the Cost Basis, but the calculation for the Cost Basis is higher that the Gross Proceeds box. Not by much, but by a little. 

I'm getting a lot of conflicting info from all of the people I've spoken with today, so I thought that I would reach out here to see if I can get any advice on what to do for filling out this form. 

[AmyC]

You said a gift from your parents. This means the amount they paid could be your basis. See here for more on gift basis. 

The IRS will give you a zero for basis if you are unable to prove another one. Brokerages are not responsible. There should be a financial folder containing transactions like this. Create one now and add the notes for how you determined this basis along with any other investments you have.

Since only you know the full story, check these out:

• Publication 550, Investment Income and Expenses  - page 59 has basis of investment property
• Publication 551 (12/2022), Basis of Assets - IRS