EXHIBIT NO. 99.(a) 38

MFS SERIES TRUST X

CERTIFICATION OF AMENDMENT

TO THE DECLARATION OF TRUST

TERMINATION OF CLASS

Pursuant to Section 9.2(b) of the Amended and Restated Declaration of Trust, dated as of December 16, 2004, as amended (the “Declaration”), of MFS Series Trust X, a business trust organized under the laws of The Commonwealth of Massachusetts (the “Trust”), the undersigned, constituting a majority of the Trustees of the Trust, do hereby certify that Class T Shares of MFS Aggressive Growth Allocation Fund, MFS Blended Research Growth Equity Fund, MFS Blended Research Mid Cap Equity Fund, MFS Blended Research Small Cap Equity Fund, MFS Blended Research Value Equity Fund, MFS Conservative Allocation Fund, MFS Emerging Markets Equity Fund, MFS Growth Allocation Fund, MFS International Diversification Fund, MFS International Growth Fund, MFS International Intrinsic Value Fund, MFS Managed Wealth Fund, and MFS Moderate Allocation Fund, each a series of the Trust, have been terminated effective upon the filing of this instrument with the Secretary of State of The Commonwealth of Massachusetts.

IN WITNESS WHEREOF, a majority of the Trustees of the Trust have executed this amendment, in one or more counterparts, all constituting a single instrument, as an instrument under seal in The Commonwealth of Massachusetts, as of September 11, 2020 and further certify, as provided by the provisions of Section 9.3(c) of the Declaration, that this amendment was duly adopted by the undersigned in accordance with Section 9.3(a) of the Declaration.

Steven E. Buller	Robert J. Manning
Steven E. Buller	Robert J. Manning
c/o MFS Investment Management	MFS Investment Management
111 Huntington Avenue	111 Huntington Avenue
Boston, MA 02199	Boston, MA 02199
John A. Caroselli	Clarence Otis, Jr.
John A. Caroselli	Clarence Otis, Jr.
c/o MFS Investment Management	MFS Investment Management
111 Huntington Avenue	111 Huntington Avenue
Boston, MA 02199	Boston, MA 02199
Maureen R. Goldfarb	Maryanne L. Roepke
Maureen R. Goldfarb	Maryanne L. Roepke
c/o MFS Investment Management	c/o MFS Investment Management
111 Huntington Avenue	111 Huntington Avenue
Boston, MA 02199	Boston, MA 02199
Peter D. Jones	Robin A. Stelmach
Peter D. Jones	Robin A. Stelmach
c/o MFS Investment Management	MFS Investment Management
111 Huntington Avenue	111 Huntington Avenue
Boston, MA 02199	Boston, MA 02199
John P. Kavanaugh	Laurie J. Thomsen
John P. Kavanaugh	Laurie J. Thomsen
c/o MFS Investment Management	c/o MFS Investment Management
111 Huntington Avenue	111 Huntington Avenue
Boston, MA 02199	Boston, MA 02199
James W. Kilman, Jr.
James W. Kilman, Jr.
c/o MFS Investment Management
111 Huntington Avenue
Boston, MA 02199