Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Are these scenarios considered as taxable income?
For case 1, there is no tax due as you sold the book for less than your cost basis. If you had sold for more than $100, then you would have had a profit. For case 2, that depends on the value of the gift card with respect to the value of your fare. Most likely that gift card is less than the cost of the fare. And in that case it would generally be treated as a reduction in the purchase price. The same way that rebates and cash back on credit card are treated. Note if for some reason a 1099 was generated that would change the situation and you would need to consult a tax professional. Since that would indicate that the other party to the transaction had a different view of the situation.