Chelsea contributed $400,000 to an irrevocable trust with no retained powers in 2015 and did not retain any powers over the transferred assets. She named her only son as the sole income and remainder beneficiary and paid gift tax at the date of the transfer of $25,000. In 2016, Chelsea died of breast cancer. The fair market value of the property in the irrevocable trust was $3,000,000 at the date of her death. What is the value of assets that are included in Chelsea's gross estate? Why?