I sold a mutual fund in 2022 (with JP Morgan). Their 1099-B included cost basis for shares acquired in recent time (from 2012) but not for older shares (I believe this is due to the fund being with Washinton Mutual before JP Morgan took over). The form says "Report on Form 8949, Code X**-Either Part I or Part II with Box B or Box E checked". I do have old records and know what the basis was. Do I just ignore JP's form and enter the Proceed and Basis myself? Because I have no idea how to report on Form 8949 as suggested.
I also noticed that the basis for shares that were acquired in 2021 (short term capital gain) is less than what I paid to acquire those shares. I have no idea how JP Morgan determines the Basis. Can I make correction in Turbo Tax ? Thank you.
