* Properties must be "like kind"

* Both properties must be held for productive business use or investment

* The titleholder of the sale property must be the same titleholder of the purchased property.

* Within 45 days of the sale of the relinquished property, a replacement property (or properties) must be identified in writing.

* Within the earlier of 180 days of the sale of the relinquished property or the due date for the taxpayer's tax return for the taxable year in which the transfer of the relinquished property occurs, the replacement properties must be purchased. (In some cases, the taxpayer must file for an extension to file his taxes, but in no case will the 180 day period be extended.)