Unless otherwise directed by the decedent in his will, a representative may join with the spouse of the decedent or of the ward in the making of a joint federal or state income tax return for the decedent or ward and his spouse and to consent for federal or state gift tax purposes to gifts made by the spouse of the decedent or ward to the end that gifts to which consent is given are treated for federal or state gift tax purposes as made 1/2 by the decedent or ward and 1/2 by his spouse. Any liability incurred by a representative pursuant to any such joinder or consent is incurred on behalf of the estate of the decedent or ward and not individually.
755 ILCS 5/27-7