I want to know if I have to pay taxes on this sale and how do I calculate this and what form to use. I have owned the land for 15 years and I purchased it with some other lots adjoining it. I have recently divorced and do not know exactly how much we paid for the land. I have a 1099S form and I just cannot see where I need to calculate if this was a gain or loss and if I have to add to my income if I made money on this.