Further information from instructions for the person responsible for closing the transaction -
A sample certification format can be found in Revenue Procedure 2007-12, 2007-4 I.R.B. 354, available at
Rev. Proc. 2007-12 does not reflect changes made by Public Law
110-289, section 3092(a), which added section 121(b)(4 [sic (5)]). The sample certification included in Rev. Proc. 2007-12 does not include an assurance that there has been no period of nonqualified use (as that term is defined in section 121(b)(4 [sic (5)])(C)) after December 31, 2008. Also, the sample certification included in Rev. Proc. 2007-12 does not include an assurance, as required by section 6045(e)(5)(A)(iii), that the full amount of the gain from the sale is excludable under section 121.
You may get the certification any time on or before January 31 of the year after the year of sale. You may rely on the certification and not file or furnish Form 1099-S unless you know that any assurance on the certification is incorrect.
You must keep the certification for 4 years after the year of sale. You may keep the certification on paper, microfilm, microfiche, or in an electronic storage system.
You are not required to obtain the certification. However, if you do not obtain it, you must file and furnish Form 1099-S.