**The information below has not been verified for the 2020 tax year as the IRS Pub. 550 has not yet been released by the IRS.**
Your actual adjusted basis may be different from what is reported on Form 1099-B Proceeds From Broker and Barter Exchange Transactions.
Per IRS Publication 550 Investment Income and Expenses (Including Capital Gains and Losses), on page 40:
Stocks and Bonds
The basis of stocks or bonds you own is generally the purchase price plus the costs of purchase, such as commissions and recording or transfer fees. If you acquired stock or bonds other than by purchase, your basis is usually determined by fair market value or the previous owner's adjusted basis as discussed earlier under Basis Other Than Cost.
The basis of stock must be adjusted for certain events that occur after purchase. For example, if you receive more stock from nontaxable stock dividends or stock splits, you must reduce the basis of your original stock. You must also reduce your basis when you receive nondividend distributions (discussed in chapter 1). These distributions, up to the amount of your basis, are a nontaxable return of capital.
Note. Form 1099-B, received from your broker, usually reports the full gain or loss on the transaction (if it provides purchase information at all) and does not usually take into account any fees. Therefore, your adjusted basis may be different from what is reported on the Form 1099-B.
Note that any link in the information above is updated each year automatically and will take you to the most recent version of the document at the time it is accessed.