INTERNAL CONTROL RPT

REPORT OF INDEPENDENT REGISTERED PUBLIC
ACCOUNTING FIRM

To the Board of Trustees of MFS Series Trust XIII and the
Shareholders of MFS Government Securities Fund:

In planning and performing our audit of the financial
statements of the MFS Government Securities Fund as of
and for the year ended February 28, 2023, in accordance
with the standards of the Public Company Accounting
Oversight Board (United States), we considered the
Fund's internal control over financial reporting, including
controls over safeguarding securities, as a basis for
designing our auditing procedures for the purpose of
expressing our opinion on the financial statements and to
comply with the requirements of Form N-CEN, but not for
the purpose of expressing an opinion on the effectiveness
of the Fund's internal control over financial reporting.
Accordingly, we express no such opinion.

The management of the Fund is responsible for
establishing and maintaining effective internal control
over financial reporting.  In fulfilling this responsibility,
estimates and judgments by management are required to
assess the expected benefits and related costs of
controls.  A fund's internal control over financial reporting
is a process designed to provide reasonable assurance
regarding the reliability of financial reporting and the
preparation of financial statements for external purposes
in accordance with generally accepted accounting
principles.  A fund's internal control over financial
reporting includes those policies and procedures that (1)
pertain to the maintenance of records that, in reasonable
detail, accurately and fairly reflect the transactions and
dispositions of the assets of the fund; (2) provide
reasonable assurance that transactions are recorded as
necessary to permit preparation of financial statements in
accordance with generally accepted accounting principles,
and that receipts and expenditures of the fund are being
made only in accordance with authorizations of
management of the fund and trustees of the trust; and
(3) provide reasonable assurance regarding prevention or
timely detection of unauthorized acquisition, use, or
disposition of a fund's assets that could have a material
effect on the financial statements.

Because of its inherent limitations, internal control over
financial reporting may not prevent or detect
misstatements.  Also, projections of any evaluation of
effectiveness to future periods are subject to the risk that
controls may become inadequate because of changes in
conditions or that the degree of compliance with the
policies or procedures may deteriorate.

A deficiency in internal control over financial reporting
exists when the design or operation of a control does not
allow management or employees, in the normal course of
performing their assigned functions, to prevent or detect
misstatements on a timely basis.  A material weakness is
a deficiency, or a combination of deficiencies, in internal
control over financial reporting, such that there is a
reasonable possibility that a material misstatement of a
fund's annual or interim financial statements will not be
prevented or detected on a timely basis.

Our consideration of the Fund's internal control over
financial reporting was for the limited purpose described
in the first paragraph and would not necessarily disclose
all deficiencies in internal control that might be material
weaknesses under standards established by the Public
Company Accounting Oversight Board (United States).
However, we noted no deficiencies in the Fund's internal
control over financial reporting and its operations,
including controls for safeguarding securities, that we
consider to be a material weakness, as defined above, as
of February 28, 2023.

This report is intended solely for the information and use
of management, the Board of Trustees of MFS Series
Trust XIII and the Securities and Exchange Commission
and is not intended to be and should not be used by
anyone other than these specified parties.

/s/ Deloitte & Touche LLP
Boston, Massachusetts
April 14, 2023

INTERNAL CONTROL RPT

Report of Independent Registered Public Accounting Firm

To the Shareholders of MFS Diversified Income Fund and
MFS New Discovery Value Fund and Board of Trustees of
MFS Series Trust XIII

In planning and performing our audit of the financial statements of MFS
Diversified Income Fund and MFS New Discovery Value Fund (the "Funds") (two of
the funds constituting MFS Series Trust XIII (the "Trust")) as of and for the
year ended February 28, 2023, in accordance with the standards of the Public
Company Accounting Oversight Board (United States) (PCAOB), we considered the
Trust's internal control over financial reporting, including controls over
safeguarding securities, as a basis for designing our auditing procedures for
the purpose of expressing our opinion on the financial statements and to comply
with the requirements of Form N-CEN, but not for the purpose of expressing an
opinion on the effectiveness of the Trust's internal control over financial
reporting. Accordingly, we express no such opinion.

The management of the Trust is responsible for establishing and maintaining
effective internal control over financial reporting. In fulfilling this
responsibility, estimates and judgments by management are required to assess
the expected benefits and related costs of controls. A company's internal
control over financial reporting is a process designed to provide
reasonable assurance regarding the reliability of financial reporting and
the preparation of financial statements for external purposes in accordance
with U.S. generally accepted accounting principles. A company's internal
control over financial reporting includes those policies and procedures
that (1) pertain to the maintenance of records that, in reasonable detail,
accurately and fairly reflect the transactions and dispositions of the
assets of the company; (2) provide reasonable assurance that transactions
are recorded as necessary to permit preparation of financial statements
in accordance with U.S. generally accepted accounting principles, and
that receipts and expenditures of the company are being made only in
accordance with authorizations of management and directors of
the company; and (3) provide reasonable assurance regarding
prevention or timely detection of unauthorized acquisition,
use or disposition of a company's assets that could have a material
effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting
may not prevent or detect misstatements. Also, projections of any evaluation
of effectiveness to future periods are subject to the risk that controls may
become inadequate because of changes in conditions, or that the degree of
compliance with the policies or procedures may deteriorate.

A deficiency in internal control over financial reporting exists when the
design or operation of a control does not allow management or employees,
in the normal course of performing their assigned functions, to prevent
or detect misstatements on a timely basis. A material weakness is a
deficiency, or a combination of deficiencies, in internal control over
financial reporting, such that there is a reasonable possibility that a
material misstatement of the Trust's annual or interim financial
statements will not be prevented or detected on a timely basis.

Our consideration of the Trust's internal control over financial reporting
was for the limited purpose described in the first paragraph and would not
necessarily disclose all deficiencies in internal control that might be
material weaknesses under standards established by the (PCAOB). However,
we noted no deficiencies in the Trust's internal control over financial
reporting and its operation, including controls over safeguarding
securities, that we consider to be a material weakness as defined above
as of February 28, 2023.

This report is intended solely for the information and use of management
and the Board of Trustees of MFS Series Trust XIII and the Securities
and Exchange Commission and is not intended to be and should not be used
by anyone other than these specified parties.

/s/ Ernst & Young LLP
Boston, Massachusetts
April 14, 2023