This is a relatively new form and ProSeries only works for simple situations. My client exchanged one property for 50 properties. Part I, Line 8 is supposed to equal the sum of Part III, Line 10. This would work if the taxpayer only exchanged with three properties. However, if the exchange is with more properties, the calculation does not work! The form 3840 should have a link so that you can add other properties to the exchange if you traded for more than three properties.
