Connecticut taxable income derived from or connected with sources within Connecticut of a nonresident trust or estate

(a) The Connecticut taxable income derived from or connected with sources within this state of a nonresident trust or estate is (1) its share of the items of income, gain, loss and deduction derived from or connected with Connecticut sources, as determined under § 12-714(a)-1 or § 12-714(b)-1 of this Part, plus or minus (2) the sum of the items of income, gain, loss and deduction derived from or connected with Connecticut sources, as determined under § 12-713(a)-3 of this Part, which would be included in federal adjusted gross income if the trust or estate were an individual but which are excluded from federal distributable net income, plus (3) in the case of a trust, includible gain (as defined under section 644 of the Internal Revenue Code) derived from or connected with Connecticut sources.