PIONEER MULTI-ASSET ULTRASHORT INCOME FUND

                      (a series of Pioneer Series Trust X)

                     Multiple Class Plan Pursuant to Rule 18f-3
                   Class A Shares, Class C Shares, Class C2 Shares,
                   Class K Shares, Class Y Shares and Class Z Shares

                               June 1, 2013

     Each class of shares of Pioneer Multi-Asset Ultrashort Income Fund (the
"Fund") will have the same relative rights and privileges and be subject to the
same sales charges, fees and expenses, except as set forth below. The Board of
Trustees may determine in the future that other distribution arrangements,
allocations of expenses (whether ordinary or extraordinary) or services to be
provided to a class of shares are appropriate and amend this Multiple Class Plan
accordingly without the approval of shareholders of any class. Except as set
forth in the Fund's prospectus(es), shares may be exchanged only for shares of
the same class of another Pioneer mutual fund.

     Article I. Class A Shares

     Class A Shares are sold at net asset value per share and subject to the
initial sales charge schedule or contingent deferred sales charge ("CDSC") and
minimum purchase requirements as set forth in the Fund's prospectus. Class A
Shares shall be entitled to the shareholder services set forth from time to time
in the Fund's prospectus with respect to Class A Shares. Class A Shares are
subject to fees calculated as a stated percentage of the net assets attributable
to Class A Shares under the Fund's Class A Rule 12b-1 Distribution Plan as set
forth in such Distribution Plan. The Class A Shareholders have exclusive voting
rights, if any, with respect to the Fund's Class A Rule 12b-1 Distribution Plan.
Transfer agency fees are allocated to Class A Shares on a per account basis
except to the extent, if any, such an allocation would cause the Fund to fail to
satisfy any requirement necessary to obtain or rely on a private letter ruling
from the Internal Revenue Service ("IRS") relating to the issuance of multiple
classes of shares. Class A Shares shall bear the costs and expenses associated
with conducting a shareholder meeting for matters relating to Class A Shares.

     The initial purchase date for Class A Shares acquired through (i)
reinvestment of dividends on Class A Shares or (ii) exchange from another
Pioneer mutual fund will be deemed to be the date on which the original Class A
Shares were purchased.

     Article II. Class C Shares

     Class C Shares are sold at net asset value per share without the imposition
of an initial sales charge. Class C Shares are sold subject to the minimum
purchase requirements set forth in the Fund's prospectus. Class C Shares shall
be entitled to the shareholder services set forth from time to time in the
Fund's prospectus with respect to Class C Shares. Class C Shares are subject to
fees calculated as a stated percentage of the net assets attributable to Class C
Shares under the Class C Rule 12b-1 Distribution Plan as set forth in such



Distribution Plan. The Class C Shareholders of the Fund have exclusive voting
rights, if any, with respect to the Fund's Class C Rule 12b-1 Distribution Plan.
Transfer agency fees are allocated to Class C Shares on a per account basis
except to the extent, if any, such an allocation would cause the Fund to fail to
satisfy any requirement necessary to obtain or rely on a private letter ruling
from the IRS relating to the issuance of multiple classes of shares. Class C
Shares shall bear the costs and expenses associated with conducting a
shareholder meeting for matters relating to Class C Shares.

     The initial purchase date for Class C Shares acquired through (i)
reinvestment of dividends on Class C Shares or (ii) exchange from another
Pioneer mutual fund will be deemed to be the date on which the original Class C
Shares were purchased.

 Article III. Class C2 Shares

    Class C2 Shares are sold at net asset value per share without the imposition
of an initial sales charge. Class C2 Shares redeemed within one (1) year of
purchase will be subject to a CDSC as set forth in the Fund's prospectus. Class
C2 Shares are sold subject to the minimum purchase requirements set forth in the
Fund's prospectus. Class C2 Shares shall be entitled to the shareholder services
set forth from time to time in the Fund's prospectus with respect to Class C2
Shares. Class C2 Shares are subject to fees calculated as a stated percentage of
the net assets attributable to Class C2 Shares under the Class C2 Rule 12b-1
Distribution Plan as set forth in such Distribution Plan. The Class C2
Shareholders of the Fund have exclusive voting rights, if any, with respect to
the Fund's Class C2 Rule 12b-1 Distribution Plan. Transfer agency fees are
allocated to Class C2 Shares on a per account basis except to the extent, if
any, such an allocation would cause the Fund to fail to satisfy any requirement
necessary to obtain or rely on a private letter ruling from the IRS relating to
the issuance of multiple classes of shares. Class C2 Shares shall bear the
costs and expenses associated with conducting a shareholder meeting for matters
relating to Class C2 Shares.

     The initial purchase date for Class C2 Shares acquired through (i)
reinvestment of dividends on Class C2 Shares or (ii) exchange from another
Pioneer mutual fund will be deemed to be the date on which the original Class C2
Shares were purchased.

Article IV. Class K Shares

     Class K Shares are sold at net asset value per share without the imposition
of an initial sales charge. Class K Shares are not subject to a CDSC upon
redemption regardless of the length of the period of time such shares are held.
Class K Shares are sold subject to the minimum purchase requirements set forth
in the Fund's prospectus. Class K Shares shall be entitled to the shareholder
services set forth from time to time in the Fund's prospectus with respect to
Class K Shares.

     Class K Shares are not subject to fees payable under a distribution or
other plan adopted pursuant to Rule 12b-1 under the Investment Company Act of
1940, as amended (the "Act").

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The Class K Shareholders of the Fund have exclusive voting rights, if any, with
respect to the Fund's possible future adoption of a Class K Rule 12b-1
Distribution Plan. Transfer agency fees are allocated to Class K Shares on a per
account basis except to the extent, if any, such an allocation would cause the
Fund to fail to satisfy any requirement necessary to obtain or rely on a private
letter ruling from the IRS relating to the issuance of multiple classes of
shares. Class K Shares shall bear the costs and expenses associated with
conducting a shareholder meeting for matters relating to Class K Shares.

     The initial purchase date for Class K Shares acquired through (i)
reinvestment of dividends on Class K Shares or (ii) exchange from another
Pioneer mutual fund will be deemed to be the date on which the original Class K
Shares were purchased.

     Article V. Class Y Shares

     Class Y Shares are sold at net asset value per share without the imposition
of an initial sales charge. Class Y Shares are not subject to a CDSC upon
redemption regardless of the length of the period of time such shares are held.
Class Y Shares are sold subject to the minimum purchase requirements set forth
in the Fund's prospectus. Class Y Shares shall be entitled to the shareholder
services set forth from time to time in the Fund's prospectus with respect to
Class Y Shares.

     Class Y Shares are not subject to fees payable under a distribution or
other plan adopted pursuant to Rule 12b-1 under the Act. The Class Y
Shareholders of the Fund have exclusive voting rights, if any, with respect to
the Fund's possible future adoption of a Class Y Rule 12b-1 Distribution Plan.
Transfer agency fees are allocated to Class Y Shares on a per account basis

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except to the extent, if any, such an allocation would cause the Fund to fail to
satisfy any requirement necessary to obtain or rely on a private letter ruling
from the IRS relating to the issuance of multiple classes of shares. Class Y
Shares shall bear the costs and expenses associated with conducting a
shareholder meeting for matters relating to Class Y Shares.

     The initial purchase date for Class Y Shares acquired through (i)
reinvestment of dividends on Class Y Shares or (ii) exchange from another
Pioneer mutual fund will be deemed to be the date on which the original Class Y
Shares were purchased.

  Article VI. Class Z Shares

     Class Z Shares are sold at net asset value per share without an initial
sales charge. Class Z Shares are not subject to a CSDC upon redemption
regardless of the length of period of time such Shares are held. Class Z Shares
are sold to mutual fund wrap programs and similar programs offered through
financial intermediaries and other investors that meet the eligibility
requirements for Class Z Shares set forth in the Fund's prospectus. Class Z
Shares shall be entitled to the shareholder services set forth from time to time
in the Fund's prospectus with respect to Class Z Shares.

     Class Z Shares are not subject to fees payable under a distribution or
other plan adopted pursuant to Rule 12b-1 under the Act. The Class Z
Shareholders of the Fund have exclusive voting rights, if any, with respect to
the Fund's possible future adoption of a Class Z Rule 12b-1 Distribution Plan.
Transfer agency fees are allocated to Class Z Shares on a per account basis
except to the extent, if any, such an allocation would cause the Fund to fail to
satisfy any requirement necessary to obtain or rely on a private letter ruling
from the IRS relating to the issuance of multiple classes of shares. Class Z
Shares shall bear the costs and expenses associated with conducting a
shareholder meeting for matters relating to Class Z Shares.

     The initial purchase date for Class Z Shares acquired through (i)
reinvestment of dividends on Class Z Shares or (ii) exchange from another
Pioneer mutual fund will be deemed to be the date on which the original Class Z
Shares were purchased.

     Article VII. Approval by Board of Trustees

     This Multiple Class Plan shall not take effect until it has been approved
by the vote of a majority (or whatever greater percentage may, from time to
time, be required under Rule 18f-3 under the Act) of (a) all of the Trustees of
the Fund and (b) those of the Trustees who are not "interested persons" (as such
term may be from time to time defined under the Act) of the Fund.

     Article VIII. Amendments

     No material amendment to this Multiple Class Plan shall be effective unless
it is approved by the Board of Trustees of the Fund in the same manner as is
provided for approval of this Multiple Class Plan in Article VII.

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