Settlement Trust Improvement Act of 2017 This bill amends the Internal Revenue Code, with respect to the tax treatment of Alaska Native Settlement Trusts, to: (1) allow an Alaska Native Corporation to assign certain payments referenced in the Alaska Native Claims Settlement Act to a trust without including the payments in the gross income of the corporation, (2) allow the corporation to elect annually to deduct contributions made to a trust, (3) allow a trust to elect to defer the recognition of gains related to contributions of property other than cash until the sale or exchange of the property, and (4) establish information reporting requirements for deductible contributions to a trust.