REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Board of Trustees of MFS Series Trust XIV and the Shareholders
of MFS Institutional Money Market Portfolio:

In planning and performing our audit of the financial statements of MFS
Institutional Money Market Portfolio (a series of MFS Series Trust XIV)
(the "Fund") as of and for the year ended August 31, 2022, 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
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 operation,
including controls for safeguarding securities, that we consider
to be a material weakness, as defined above, as of August 31, 2022.

This report is intended solely for the information and use
of management, the Board of Trustees of MFS Series Trust XIV
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
October 17, 2022