The boards of regents of the state universities, the boards of trustees of the regional universities and of The Evergreen State College, the student achievement council, or the state board for community and technical colleges shall not pay any amount to be added to the annuity or retirement income plan of any retired person who was first hired on or after July 1, 2011, or who has served for less than ten years in one or more of the state institutions of higher education. In the case of persons who have served more than ten years but less than twenty-five years no amount shall be paid in excess of four percent of the amount authorized in RCW
28B.10.400(1)(c), multiplied by the number of years of full-time service rendered by such person: PROVIDED, That credit for years of service at an institution of higher education shall be limited to those years in which contributions were made by a faculty member or other employee designated pursuant to RCW
28B.10.400(1)(a) and the institution or the state as a result of which a benefit is being received by a retired person from any Washington state public retirement plan: PROVIDED FURTHER, That all such benefits that a retired person is eligible to receive shall reduce any supplementation payments provided for in RCW
28B.10.400.