International Paper sponsors and maintains the Retirement Plan of International Paper Company (the Pension Plan), a tax-qualified defined benefit pension plan that provides retirement benefits to substantially all U.S. salaried employees and hourly employees (receiving salaried benefits) hired prior to July 1, 2004, and substantially all other U.S. hourly and union employees who work at a participating business unit regardless of hire date. These employees generally are eligible to participate in the Pension Plan upon attaining 21 years of age and completing one year of eligibility service. U.S. salaried employees and hourly employees (receiving salaried benefits) hired after June 30, 2004, are not eligible for the Pension Plan, but receive a company contribution to their individual savings plan accounts; however, salaried employees hired by Temple Inland prior to March 1, 2007 or Weyerhaeuser Company's Cellulose Fibers division prior to December 1, 2011 also participate in the Pension Plan.

The Pension Plan provides defined pension benefits based on years of credited service and either final average earnings (salaried employees and hourly employees receiving salaried benefits), hourly job rates or specified benefit rates (hourly and union employees).

The Company will freeze participation, including credited service and compensation, for salaried employees under the Pension Plan, the Pension Restoration Plan and the two SERP plans for all service on or after January 1, 2019. This change will not affect benefits accrued through December 31, 2018.

Net periodic pension expense for our qualified and nonqualified U.S. defined benefit plans comprised the following:



	Three Months Ended March 31,
In millions	2018			2017
Service cost	$	38		$	40
Interest cost	118			138
Expected return on plan assets	(200		)	(192		)
Actuarial loss	82			85
Amortization of prior service cost	4			7
Net periodic pension expense	$	42		$	78

The components of net periodic pension expense other than the service cost component are included in Non-operating pension expense in the Consolidated Statement of Operations.

The Company’s funding policy for our pension plans is to contribute amounts sufficient to meet legal funding requirements, plus any additional amounts that the Company may determine to be appropriate considering the funded status of the plan, tax deductibility, the cash flows generated by the Company, and other factors. No cash contributions were made to the qualified pension plan in the first three months of 2018 and 2017. The nonqualified defined benefit plans are funded to the extent of benefit payments, which totaled $14 million for the three months ended March 31, 2018.