obviously, he did not do an exchange, but his LAWYER/EXCHANGE FACILITAOR says he did. Form 8824 line 18, just entering the items shown on Lacerte and also the form, do not seem to be complete.  what should I put on line 18?  Here is exactly what our Esteemed  Barrister wrote:   " sells property that has a 900,000 mortgage, but only a 500,000 basis on it for 1,000,000 and receiving 100K in net proceeds.  Then pays 100 K to buy replacement property for 100k, . 100 k of the capital gain from first property is deferred to 2nd property, the rest of the capital gain is taxed"     Then he continues " however if our guy used the  entire 100 K for the down payment on a 500,000 property, and financed the remaining 400K of the purchase price, then the entire capital gain is deferred onto the new property, (which will then have a cost basis of zero)"