Report of Independent Registered Public Accounting Firm


To the Shareholders and Board of Trustees of

Pioneer Asset Allocation Trust

In planning and performing our audits of the financial statements of Pioneer
Solutions - Balanced Fund (the "Portfolio") (one portfolio constituting Pioneer
Asset Allocation Trust) as of and for the year ended July 31, 2018, in
accordance with the standards of the Public Company Accounting Oversight Board
(United States), we considered the Portfolio'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
Portfolio's internal control over financial reporting.
Accordingly, we express no such opinion.


The management of the Portfolio 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 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 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 company's annual or interim financial statements will not be prevented
or detected on a timely basis.

Our consideration of the Portfolio'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 Portfolio'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 July 31, 2018.

This report is intended solely for the information and use of management and the
Board of Directors of Pioneer Asset Allocation Trust, 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

September 28, 2018