OK TurboTax what is the answer? This guy and now I are waiting for an answer. Please pay attention to your customers' questions or other companies will. In certain situations that number, positive or negative, is not used as the ACB has already been calculated and is only reported here for info. People who must do the calc themselves may need to enter a negative number. Regardless, why not be able to do so or give an explanation!??? The CRA says to use a negative number yet your software cannot handle one, so what confidence should we have that other aspects of our tax calc are being handled properly? Not impressed.