Your account may have a negative balance for several reasons. As a performer member, another performer might have made a successful claim on a recording you are currently linked to; you might have been listed incorrectly on a recording and been removed; or there might have been a change in your contribution category or listed country of residence.
As a recording rightsholder member, your recordings may have been transferred to another member; performers may have been added to your track; or you may have been paid an advance by PPL that your distribution did not match.