[FORM OF OPINION OF BINGHAM McCUTCHEN LLP]


[     ], 2014

Pioneer Ibbotson Asset Allocation Series
60 State Street
Boston, Massachusetts  02109


Ladies and Gentlemen:

This opinion is furnished to you pursuant to Paragraph 8.4 of the Agreement and
Plan of Reorganization (the "Agreement"), dated as of [ ], 2014, by and between
Pioneer Ibbotson Asset Allocation Series, a Delaware statutory trust (the
"Trust"), on behalf of Pioneer Ibbotson Growth Allocation Fund, a series thereof
(the "Acquiring Fund"), and the Trust, on behalf of Pioneer Ibbotson Aggressive
Asset Allocation Fund, a series thereof (the "Acquired Fund"). All capitalized
terms not otherwise defined herein have the meanings ascribed to them in the
Agreement. The Agreement contemplates (1) the transfer of all of the Acquired
Assets to the Acquiring Fund in exchange solely for (a) the issuance to the
Acquired Fund of a number of Class A, Class C, and Class Y Acquiring Fund
Shares, including fractional Acquiring Fund Shares, having an aggregate NAV
equal to the NAV of the Acquired Fund attributable to the corresponding classes
of Acquired Fund Shares, and (b) the assumption by the Acquiring Fund of all of
the Assumed Liabilities, and (2) the distribution by the Acquired Fund of the
Acquiring Fund Shares pro rata on a class-by-class basis to the Acquired Fund
Shareholders in complete liquidation and dissolution of the Acquired Fund
(collectively, the "Transaction").

In connection with this opinion we have examined and relied upon the originals
or copies, certified or otherwise identified to us to our satisfaction, of the
Agreement, the Combined Information Statement of the Acquired Fund and
Prospectus for the Acquiring Fund, dated [ ], 2014, and related documents
(collectively, the "Transaction Documents"). In that examination, we have
assumed the genuineness of all signatures, the capacity and authority of each
party executing a document to so execute the document, the authenticity and
completeness of all documents purporting to be originals (whether reviewed by us
in original or copy form) and the conformity to the originals of all documents
purporting to be copies (including electronic copies). We have also assumed that
each agreement and other instrument reviewed by us is valid and binding on the
party or parties thereto and is enforceable in accordance with its terms, and
that there are no contracts, agreements, arrangements, or understandings, either
written or oral, that are inconsistent with or that would materially alter the
terms of the Agreement or the other Transaction Documents.

As to certain factual matters, we have relied with your consent upon, and our
opinion is limited by, the representations of the various parties set forth in
the Transaction Documents and in certificates of the Trust, on behalf of the
Acquired Fund and the Acquiring Fund, each dated as of the date hereof (the
"Certificates"). Our opinion assumes (i) that all representations set forth in
the Transaction Documents and in the



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Certificates will be true and correct in all material respects as of the date of
the Transaction (and that any such representations made "to the best knowledge
of," "to the knowledge of," "in the belief of," or otherwise similarly
qualified, are true and correct in all material respects without any such
qualification), and (ii) that the Agreement is implemented in accordance with
its terms and consistent with the representations set forth in the Transaction
Documents and Certificates. Our opinion is limited solely to the provisions of
the Internal Revenue Code of 1986, as amended and as presently in effect (the
"Code"), existing case law, existing permanent and temporary treasury
regulations promulgated under the Code ("Treasury Regulations"), and existing
published revenue rulings and procedures of the Internal Revenue Service that
are in effect as of the date hereof, all of which are subject to change and new
interpretation, both prospectively and retroactively. We assume no obligation to
update our opinion to reflect other facts or any changes in law or in the
interpretation thereof that may hereafter occur.

On the basis of and subject to the foregoing, with respect to the Transaction,
we are of the opinion that, for United States federal income tax purposes:

     1.   The Transaction will constitute a "reorganization" within the meaning
          of Section 368(a) of the Code, and each of the Acquired Fund and the
          Acquiring Fund will be a "party to a reorganization" within the
          meaning of Section 368(b) of the Code.

     2.   No gain or loss will be recognized by the Acquired Fund on the
          transfer of the Acquired Assets to the Acquiring Fund solely in
          exchange for the Acquiring Fund Shares and the assumption by the
          Acquiring Fund of the Assumed Liabilities, or upon the distribution of
          the Acquiring Fund Shares to the shareholders of the Acquired Fund,
          except for (A) gain or loss that may be recognized on the transfer of
          "section 1256 contracts" as defined in Section 1256(b) of the Code,
          (B) gain that may be recognized on the transfer of stock in a "passive
          foreign investment company" as defined in Section 1297(a) of the Code,
          and (C) any other gain or loss that may be required to be recognized
          as a result of the closing of the Acquired Fund's taxable year or upon
          the transfer of an Acquired Asset regardless of whether such transfer
          would otherwise be a non-recognition transaction under the Code.

     3.   The tax basis in the hands of the Acquiring Fund of each Acquired
          Asset will be the same as the tax basis of such Acquired Asset in the
          hands of the Acquired Fund immediately prior to the transfer thereof,
          increased by the amount of gain (or decreased by the amount of loss),
          if any, recognized by the Acquired Fund on the transfer.

     4.   The holding period of each Acquired Asset in the hands of the
          Acquiring Fund, other than any Acquired Asset with respect to which
          gain or loss is required to be recognized in the Transaction, will
          include the period during which such Acquired Asset was held by the
          Acquired Fund



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          (except where investment activities of the Acquiring Fund have the
          effect of reducing or eliminating the holding period with respect to
          an Acquired Asset).

     5.   No gain or loss will be recognized by the Acquiring Fund upon its
          receipt of the Acquired Assets solely in exchange for Acquiring Fund
          Shares and the assumption of the Assumed Liabilities.

     6.   No gain or loss will be recognized by the Acquired Fund Shareholders
          upon the exchange of all of their Acquired Fund Shares for Acquiring
          Fund Shares as part of the Transaction.

     7.   The aggregate tax basis of the Acquiring Fund Shares that each
          Acquired Fund Shareholder receives in the Transaction will be the same
          as the aggregate tax basis of the Acquired Fund Shares exchanged
          therefor.

     8.   Each Acquired Fund Shareholder's holding period for the Acquiring Fund
          Shares received in the Transaction will include the holding period for
          the Acquired Fund Shares exchanged therefor, provided that the
          Acquired Fund Shareholder held such Acquired Fund Shares as capital
          assets on the date of the exchange.

This opinion is being delivered solely to you for your use in connection with
the Transaction, and may not be relied upon by any other person or used for any
other purpose.

Very truly yours,



BINGHAM McCUTCHEN LLP