You, however, do.

It is important that the information in bivio is correct.

If your broker does not show cost basis information on your 1099 in this section, of course it won't agree with what bivio is showing. (But you don't get to ignore it)

To verify whether bivio is showing the correct information, you need to find something to compare to somewhere other than on your 1099.

Most brokers now have a realized gain/loss report that shows cost basis by lot (this is important) that you can get from them. If you bought all your shares at the same broker, it should provide information you can compare to section B or E in bivio to make sure the amounts shown are correct.

If not, you'll need to go to the brokerage statements for the months the lots involved were purchased. You'll need the information on them to confirm that the purchase transactions were entered correctly. You'll also need to look at brokerage statements for any months when reorganizations occurred to make sure those were entered correctly in bivio.

For your sale date, you'll need to know how your lots were selected for the sale. Was it FIFO, LIFO or something else? You can also get this from your brokerage.