The Tax Relief Act of 2010 allows surviving spouses of decedents dying in 2011 or subsequent years to elect to use the decedent's unused exclusion amount and add it to the surviving spouse's exclusion amount. This allows for a greater amount of the surviving spouse's estate to pass tax-free. The ability to transfer the deceased spouse's unused exclusion amount is known as "portability." Portability was made permanent in 2013. In order for a surviving spouse to take advantage of portability, he or she must file a timely Estate Tax Return, even if a return is not required because the value of the deceased spouse's estate is under the federal estate tax exemption. Until recently there has been no relief for late filings - that is, if you missed it then too bad, you just wasted the exemption. Recently the IRS has provided for late filings in limited cases. If your spouse died after December 31, 2010 and on or before December 31, 2013, and you did not file a timely Estate Tax Return to preserve your spouse's exemption, you may qualify for a late filing. (See Rev. Proc. 2014-18; 2014-7 IRB 513).