(a) In general. In determining the applicable fraction with respect to a charitable lead annuity trust—

(1) The numerator is the adjusted generation-skipping transfer tax exemption (adjusted GST exemption); and

(2) The denominator is the value of all property in the trust immediately after the termination of the charitable lead annuity.

(b) Adjusted GST exemption defined. The adjusted GST exemption is the amount of GST exemption allocated to the trust increased by an amount equal to the interest that would accrue if an amount equal to the allocated GST exemption were invested at the rate used to determine the amount of the estate or gift tax charitable deduction, compounded annually, for the actual period of the charitable lead annuity. If a late allocation is made to a charitable lead annuity trust, the adjusted GST exemption is the amount of GST exemption allocated to the trust increased by the interest that would accrue if invested at such rate for the period beginning on the date of the late allocation and extending for the balance of the actual period of the charitable lead annuity. The amount of GST exemption allocated to a charitable lead annuity trust is not reduced even though it is ultimately determined that the allocation of a lesser amount of GST exemption would have resulted in an inclusion ratio of zero. For purposes of chapter 13, a charitable lead annuity trust is any trust providing an interest in the form of a guaranteed annuity described in §25.2522(c)-3(c)(2)(vi) of this chapter for which the transferor is allowed a charitable deduction for Federal estate or gift tax purposes.

(c) Example. The following example illustrates the provisions of this section: