IRS says I owe $7000 because of under reporting income. I just plugged in numbers from my 2020 1099B into Turbotax. Proceeds seem mixed up with cost in the letter. WTD?

[ductionact-]

It seems to confuse them that stock sales are often split into tranches, not all shares at once. They have mistaken cost basis for profits in some cases.  What do I do?

[fanfare]

"Proceeds seem mixed up with cost "

Maybe you mixed up proceeds with costs when entering.

IRS does not get confused by 1099-B supplied by your broker.

What Box(es) did you check on Form 8949 ? A/D ? or B/E  ?

@ductionact- 

[Mike9241]

look at your 1099-B from your broker. there should be a column with the total realized gain/loss at the end or on some statements they have totals for the short-term and long-term portions of the gains/loss. do these match your schedule D?