8. EMPLOYEE BENEFIT PLANS

A majority of WESCO’s employees are covered by defined contribution retirement savings plans for their services rendered subsequent to WESCO’s formation. WESCO also offers a deferred compensation plan for select individuals. For U.S. participants, WESCO matches contributions made by employees at an amount equal to 50% of participants' total monthly contributions up to a maximum of 6% of eligible compensation. For Canadian participants, WESCO makes contributions in amounts ranging from 3% to 5% of participants' eligible compensation based on years of continuous service. WESCO may also make, subject to the Board of Directors' approval, a discretionary contribution to the defined contribution retirement savings plan covering U.S. participants if certain predetermined profit levels are attained. For the three months ended March 31, 2018 and 2017, WESCO incurred charges of $10.7 million and $5.5 million, respectively, for all such plans. Contributions are made in cash to employee retirement savings plan accounts. The deferred compensation plan is an unfunded plan. As of March 31, 2018 and December 31, 2017, the Company's obligation under the deferred compensation plan was $24.0 million and $24.3 million, respectively. Employees have the option to transfer balances allocated to their accounts in the defined contribution retirement savings plan and the deferred compensation plan into any of the available investment options.

The Company sponsors a contributory defined benefit plan covering substantially all Canadian employees of EECOL and a Supplemental Executive Retirement Plan (the "SERP") for certain executives of EECOL. During the three months ended March 31, 2018, the Company contributed $0.1 million to the SERP.

The following table sets forth the components of net periodic benefit costs for the defined benefit plans:



	Three Months Ended
	March 31,
(In thousands)	2018			2017
Service cost	$	1,347		$	1,068
Interest cost	1,066			962
Expected return on plan assets	(1,540		)	(1,368		)
Recognized actuarial gain	(12		)	(49		)
Net periodic benefit cost	$	861		$	613

In accordance with ASU 2017-07, as described in Note 2, the service cost of $1.3 million for the three months ended March 31, 2018 was reported as a component of selling, general and administrative expenses. The other components of net periodic benefit cost totaling a net benefit of $0.5 million for the three months ended March 31, 2018 were presented as a component of net interest and other, as described in Note 9 below. For the three months ended March 31, 2017, the Company reclassified a net benefit of $0.5 million from selling, general and administrative expenses to net interest and other. The Company used the amounts disclosed in Note 7 of the Notes to Condensed Consolidated Financial Statements in the Quarterly Report on Form 10-Q for the three months ended March 31, 2017 as the estimation basis for applying the retrospective presentation requirements.