USA Trust Estate Tax amended return

[ChetT]

I filed a 706 in March 2014. I paid $550,000 in estate taxes. The Trust contained a property that took 3 years to sell. It sold for $800,000 less than the DOD appraisal and cost an additional $700,000 in property taxes and property mantenance.
I can provide plenty more details but my main question is "Can I amend my form 706 to deduct some or all of these additional expenses?"

I'd much rather distribute some recovered 706 estate taxes instead of distributing capital gains losses through the 1041s.

Thanks in advance

 

[DTA93433]

An estate has three years from the filing date of the return or two years from the date of the last payment, whichever is later, to file for an estate tax refund.

 

[ChetT]

My original 706 was already audited and accepted. Will the IRS accept my amended return at this point? I'll save $300,000 if I can claim these "costs of sales" at this late date. I've been told that their position might be that I should take these deductions on the trust's 1041 filings but that only give me capital gain losses that the beneficiaries can't use.
Does this make sense?