You can write off an abandoned business as a loss if you signed it over for nothing and receive no compensation of any kind for it. Trump wrote off his Atlantic City casinos as an abandonment loss, even though he received a 5% stake in the successor company. A 5% stake in the successor company is not nothing. This is part of why he is being audited right now and it has been in the process of being audited for years. However, it is naive to think that anything will ever happen as a result of this.