Do regulations require people to manually recalculate cost-basis across all the accounts they own, if stocks were transferred between them?
Example: Broker A cost basis setting is set to FIFO.
I got 100 shares (vested RSUs) from my employer, my broker A sold 33 of them to cover for taxes. Vesting price $40, sale price $40 - no additional gain/loss.
Then I transfer the rest of 67 shares to broker B "as is".
Later the same year, I get 100 shares, my broker A sold 33 of them for taxes. Vesting price $45, sale price $45 - no additional gain/loss.
My broker A reports in 1099-B zero capital gain, because as far as he concerned, he sold FIFO.
However, if FIFO applies across all accounts, then second sale should have counted as $5 gain per share.
Am I required to re-calculate the second sale myself as a profitable one?
(My guess is "no" because that will render 1099-B wrong. In this case IRS wins but I suspect that reported loss this way would raise questions. Besides, it means that I am bound to do this recalculation for all future sales done by broker A or B.
Also, transfers between accounts with different cost basis methods would make no sense.)