Exhibit 10.6.4

Summary of 2017 Incentive Plans

On December 20, 2016, the Human Resources Committee (the “Committee”) of the
Pinnacle West Capital Corporation (“Pinnacle West” or the “Company”) Board of
Directors (the “Board”) approved the Pinnacle West 2017 CEO Annual Incentive
Award Plan (the “PNW Plan”), which provides an incentive award opportunity for
Donald E. Brandt, the Chairman of the Board, President, and Chief Executive
Officer of Pinnacle West and the Chairman of the Board, President and Chief
Executive Officer of Arizona Public Service Company (“APS”).  On December 21,
2016, the Board, acting on the recommendation of the Committee, approved the APS
2017 Annual Incentive Award Plan (the “APS Plan”), which includes an incentive
award opportunity for Mark A. Schiavoni, Executive Vice President and Chief
Operating Officer, James R. Hatfield, Executive Vice President and Chief
Financial Officer, David P. Falck, Executive Vice President and General Counsel
and Randall K. Edington, Executive Vice President and Advisor to the Chief
Executive Officer.

No incentive payments will be awarded under the PNW Plan or the APS Plan unless
Pinnacle West, with respect to Mr. Brandt, or APS, with respect to
Messrs. Schiavoni, Hatfield, Falck and Edington, each achieves a specified
threshold earnings level.  The Committee will evaluate the impacts of unusual or
nonrecurring adjustments to earnings in determining whether any earnings level
has been met for purposes of the PNW Plan and may make adjustments to reflect
such impacts. Earnings impacts of actions of the Arizona Corporation Commission
("ACC") in the PNW Plan year are excluded.

Mr. Brandt’s incentive award opportunity is based 62.5% on Pinnacle West’s 2017
earnings, and 37.5% on the achievement of performance goals established for all
business units of APS. Mr. Brandt has an award opportunity of 50% of his base
salary if the threshold earnings level is met. If Pinnacle West earnings exceed
the threshold level, Mr. Brandt’s award opportunity increases proportionately by
up to an additional 75% of his base salary. To the extent certain business unit
performance goals are met, Mr. Brandt has a further award opportunity of up to
75% of base salary. The business unit performance indicators for Mr. Brandt are
in the functional areas of customer service, transmission and distribution,
fossil generation, corporate resources and performance of the Palo Verde Nuclear
Generating Station. In no event may Mr. Brandt’s award exceed 200% of his base
salary.

The award opportunities for Messrs. Schiavoni, Hatfield, Falck and Edington
under the APS Plan are based on the achievement of specified 2017 APS earnings
levels and specified business unit performance goals.  Mr. Schiavoni has a
target award opportunity of up to 75% of his base salary, Mr. Hatfield has as a
target award opportunity of up to 70% of his base salary and Messrs. Falck and
Edington each have a target award opportunity of up to 65% of their base
salaries.  Messrs. Schiavoni, Hatfield, Falck and Edington may earn less or more
than the target amount, up to a maximum award opportunity of 150% of base salary
for Mr. Schiavoni, 140% for Mr. Hatfield and 130% for Messrs. Falck and
Edington, depending on the achievement of the earnings and business unit
performance goals separately or in combination, and before adjustment for
individual performance.  The business unit performance indicators that will be
considered for Messrs. Schiavoni, Hatfield, Falck and Edington are derived from
the APS critical areas of focus, as provided in its “Core” strategic framework,
in the functional areas of employees, operational excellence, customer value and
shareholder value.  The Committee may adjust targets under the APS Plan to
reflect unanticipated events or unusual or nonrecurring adjustments to earnings
that arise in the APS Plan year, including ACC rate-related impacts.

Any awards for Messrs. Brandt, Schiavoni, Hatfield, Falck and Edington will be
subject to potential forfeiture or recovery to the extent called for by the
Company’s clawback policy.