What do I classify a matured CD (Certificate of Deposit) as under the drop down menu for "What type of investment did you sell?" Stock, Bond, or Mutual Fund?

[ThomasM125]

When you enter your Form 1099-B information in TurboTax, you will have an opportunity to indicate that the cost basis is missing or wrong. Choose that option and you can then enter the correct cost basis. In your case, if the gain is reported on a Form 1099-INT as interest income, you would report that amount as the cost basis when you enter your Form 1099-B:

@kmcinish 

[kmcinish]

Thanks Thomas,

That was the route I went, but there were a couple of odd things that happened. One was that I had to enter the cost basis as a negative number to offset the sale price. Otherwise, it added it to my income and increased my tax liability. The other thing was that I got a message displayed that I would have to physically mail my 1099-B and the supporting documentation to the IRS. That seemed weird, since I always e-file. 

I ended up going back and entering the (seven) transactions separately rather than just entering the summary amount. It was a little more tedious, but I was able to enter the cost basis as a positive number and I also didn't get the notice about having to mail in documentation. I also talked to my broker and they said that they "don't have to report the cost basis", which is why it doesn't show on the 1099-B. However, they do show all of the transactions for 2024 in my final December statement. I was able to use that to enter everything in. Just seemed weird to me that they include the details and correct cost basis on my statement, but not on the (now, incomplete) 1099-B. Also a bit frustrating.

Hopefully, that will solve it, but thanks again for the reply.