The taxpayer died in 2017 before satisfying his RMD.  The spouse chose to treat his IRA as her own.  The taxpayer had basis in his IRA.  Since his IRA accounts were transferred to the spouse, the value of his accounts were $0 on 12/31/17, which is what is asked for on his Form 8606.  If I drop in $0, all his basis is recovered in 2017.  That doesn't make sense to me.  It makes more sense to drop in the value of his accounts on the date of death, let the program compute how much of the basis he can recover tax-free, and then transfer the remainder basis to the spouse.  Then on her return, take the transferred basis and let the program compute how much she can recover tax-free, using her 12/31/17 IRA value which now includes the IRAs transferred from the deceased spouse.  My problem is I can't find how to handle the deceased spouse basis situation anywhere, not in Pub 590, not in the instructions to Form 8606, or in any regulations.  I keep thinking I am missing something obvious as this cannot be anything unique.  Can someone point me to something authoritative?