The gift tax is determined at the time of transfer and therefore the lower rates allows a transfer of more assets to the remainder beneficiary without further tax. Grantor Retained Income Trust can still be used to pass a personal residence to children or nieces or nephews. However, lower rates increase the remainder value and therefore increase tax. They are not affected by rate changes. Charitable Lead Annuity Trusts pay income to a charity and the remainder goes to a non charitable remainderman.
Lower rates decrease the remainder interest and decreases tax.
Charitable Remainder Annuity Trusts pay an income based on fluctuating values of the assets. The annuity interest becomes more valuable as rates drop and hence the charitable reduction is reduced. Charitable Remainder Unitrusts and Charitable Lead Unitrusts are unaffected by rate fluctuations. Private Annuities cut the payments that the younger obligor must pay an older annuitant. The private annuity costs less to implement now.