Temporary and Term Appointments Act of 2017 This bill authorizes a federal agency to make a temporary appointment (for a period of less than one year) or term appointment (for a period of less than five years) to a position in the competitive service when the need for the services of the employee is not permanent. An agency may extend: (1) a temporary appointment for a period of not more than two years, and (2) a term appointment for a period of not more than five years. The bill also authorizes an agency to make a noncompetitive temporary appointment or a noncompetitive term appointment for a period of not more than 18 months when a critical hiring need exists. The appointment may not be extended.