<PAGE>

                                                                   EXHIBIT 10.13

                              Tax Related Agreement

This agreement ("Agreement") is entered into as of March 6, 1998 among CWS
Communities LP, a Delaware limited partnership, the individuals and entities
having executed this Agreement on the signature pages hereto (each, a
"Contributor" and collectively "Contributors"). Each Contributor will have the
rights and obligations of a Contributor set forth herein upon such party's
execution of a counterpart signature page hereto.

Recitals:

     A.   Pursuant to that Contribution Agreement relating to the formation and
          capitalization of CWS Communities Trust of even date herewith among
          Security Capital U.S. Reality, a Luxembourg corporation, Security
          Capital Holdings S.A., a Luxembourg corporation, Clayton, Williams &
          Sherwood, Inc., a California corporation, CWS Communities Trust, a
          Maryland real estate investment trust, Operation Partnership, CWS
          Communities Incorporated, a Delaware corporation, CWS Management
          Services Incorporated, a Delaware corporation and certain individuals
          and entities, including the Contributors, the Contributors have
          contributed to the Operating Partnership certain properties described
          in Schedule A attached hereto (as each is contributed, a "Contributed
          Property, and collectively, the Contributed Properties).

     B.   Contributors and the Operating Partnership desire to enter into this
          Agreement to set forth certain terms and conditions upon which the
          Operating Partnership agrees to hold, encumber and dispose of the
          Contributed Properties.

Agreement:

     1.1  Limitation on Sale of Contributed Property

          (a)  Operating Partnership will not sell, transfer, exchange or
               otherwise dispose of part or all of its interest in any
               Contributed Property during the period (the "Lockout Period")
               commencing, with respect to each Contributed Property, on the
               date such property was contributed to the Operating Partnership
               ("Closing Date") and ending on the tenth (10th) anniversary of
               such date, subject to earlier termination as provided below,
               except in connection with either a like-kind exchange of the
               Contributed Property pursuant to Section 1031 of the Internal
               Revenue Code of 1986, as amended (the "Code") or other
               disposition that pursuant to a nonrecognition provision in the
               Code does not result in the current recognition of any gain to
               the Contributors. Notwithstanding anything to the contrary set
               forth herein, the prohibition against the sale, transfer,
               exchange or other disposition by Operating Partnership with
               respect to any Contributed Property and any obligation in
               subparagraphs (b), (c) and (d) below and in Paragraph 1.2 shall
               automatically terminate in the event that (i) the Contributors at
               any time exercise their right under the Agreement of Limited
               Partnership of the Operating Partnership to exchange, in

<PAGE>

               one or multiple transactions, 95 percent of the total number of
               Units ( as defined in the Contribution Agreement) held by the
               Contributors (the "Contributors' Units") for Class A Shares (as
               defined in the Contribution Agreement), or (ii) the Contributors
               at any time effect a taxable sale, transfer, assignments or other
               disposition of, in one or multiple transactions, 95 percent of
               the Contributors' Units, including an exchange into Class A
               Shares described in clause (i) and upon foreclosure with respect
               thereto (but excluding a pledge or other grant of security
               interest in the Contributors' Units).

          (b)  After the Lockout Period with respect to any Contributed
               Property, the Operating Partnership agrees to use commercially
               reasonable efforts without undue sacrifice to effect any
               disposition of such Contributed Property through a disposition
               pursuant to Section 1031 of the Code or other nonrecognition
               disposition described above. The Operating Partnership shall not
               be bound by the preceding sentence if a suitable exchange
               property is not located and designated by the Operating
               Partnership within 6 months after its determination to attempt to
               dispose of such Contributed Property

          (c)  If the Operating Partnership does not effect a disposition of a
               Contributed Property pursuant to subparagraph (b) above but
               nevertheless intends to dispose of a Contributed Property, then
               the Operating Partnership shall so notify the Contributors in
               writing and the Contributors shall have the right, by written
               notice delivered to the Operating Partnership within 30 days
               after receipt of such notice from the Operating Partnership, to
               exercise their right to redeem the Contributors' Units for such
               Contributed Property in accordance with the following provisions.
               Failure of the Contributors to deliver such notice during the
               30-day period shall be deemed to constitute waiver of this
               redemption right with respect to such Contributed Property. The
               notice given by the Operating Partnership to Contributors shall
               include the sales price that the Operating Partnership intends to
               offer to sell, or to accept an offer to purchase, the Contributed
               Property.

          (d)  If the Contributors elect to exercise their redemption right,
               within 30 days after such election the Operating Partnership
               shall sell and convey the Contributed Property to the
               Contributors in redemption of and exchange for a number of
               Contributors' Units allocated among the Contributors in
               proportion to the number of Units held by each Contributor or as
               they may otherwise agree equal to (i) the offering sales price
               set forth in the notice plus any closing costs incurred by the
               Operating Partnership divided by (ii) the Fair Market Value (as
               defined and determined according to Exhibit N-1 (Loan Agreement)
               to the Contribution Agreement) of a Class A Share as of the date
               of Contributor's election. If the Contributors do not exercise
               their redemption right, then the Operating Partnership may sell
               the Contributed Property free of this redemption right and shall
               have no obligation to renotify Contributors so long as the
               Contributed Property is sold within 9 months after Contributors'
               waiver of their redemption right, for a sales price of no less
               than 95 percent of the offering price, subject to customary
               prorations and adjustments.

     1.2  Debt Guarantee Agreement

<PAGE>

          (a)  From and after the Closing Date of each Contributed Property
               until the 10th anniversary of such Closing Date, Operating
               Partnership agrees that it will keep outstanding in accordance
               with its terms the Existing Debt described in Schedule B,
               attached hereto (or Replacement Financing, if applicable), in the
               principal amount of no less than the amount of the deficit
               balance in the capital accounts (determined in accordance with
               Section 704 of the Code and Treasury Regulations thereunder) of
               Contributors with respect to each Contributed Property plus the
               tax basis of each Contributed Property as of the date of this
               Agreement as set forth in Schedule C as of the Closing (with
               respect to each Contributed Property, the "Guaranteed Amount" and
               collectively the "Guaranteed Amounts") subject to required
               amortization payments under the Existing Debt; provided, however,
               that the foregoing limitation shall not apply if Operating
               Partnership replaces or refinances the Existing Debt with respect
               to such Contributed Property (the "Replacement Financing"), so
               long as the Replacement Financing (i) is for a principal amount
               not less than the outstanding principal balance of the Guaranteed
               Amount with respect to such Contributed Property at the time of
               its replacement, (ii) has an amortization schedule that provides
               for monthly or other periodic repayments of principal in an
               amount equal to or less than the periodic principal payments
               under the amortization schedule for the Existing Debt with
               respect to such Contributed Property in effect as of the Closing
               Date, and (iii) such Replacement Financing with respect to any
               Contributed Property shall constitute "nonrecourse debt" within
               the meaning of Treasury Regulation Section 1.752-1(a)(2)
               allocable to the Contributed Property to the extent of the
               Guaranteed Amount. For purposes of clause (iii) of the preceding
               sentence, the parties agree that any such Replacement Financing
               with respect to any contributed property shall constitute
               "nonrecourse debt" within the meaning of the Treasury Regulation
               Section 1.752-1(a)(2) to the extent of the Guaranteed Amount if
               either (x)(i) the Contributed Property is pledged as security for
               such Replacement Financing, (ii) the product of (a) the
               outstanding amount of any such Replacement Financing and (b) the
               quotient of (I) the fair market value of the Contributed Property
               (reasonably determined by the Operating Partnership) at the time
               of such Replacement Financing to (II) the sum of the fair market
               values of all of the properties (reasonably determined by the
               Operating Partnership) securing such Replacement Financing,
               equals or exceeds the Guaranteed Amount, and (iii) no partner
               (other than the Contributors) bears the economic risk of loss
               with respect to such Replacement Financing, within the meaning of
               Treasury Regulation Section 1.752-2(a) or (y)(1) the Contributed
               Property is pledged as security for such Replacement Financing
               within the meaning of Treasury Regulation Section 1.752-2(a) or
               (y)(i) the Contributed Property is pledged as security for a
               portion of such Replacement Financing, (ii) no other property is
               pledged as security for such portion of such Replacement
               Financing, and (iii) no partner (other than the Contributors)
               bear the economic risk of loss with respect to such Replacement
               Financing within the meaning of Treasury Regulation Section
               1.752-2(a).

     1.3  No Representation with Regard to Tax Treatment

          Notwithstanding any provision of this agreement, neither the Operating
          Partnership nor [CWS Communities Trust] makes any representation
          regarding (and shall have no

<PAGE>

          liability with respect to) the tax consequences to the Contributors of
          the transactions contemplated herein or in any [Related Agreements].

     1.4  Damages

          In the event that Operating Partnership breaches any of its obligation
          set forth in Paragraph 1.1 or Paragraph 1.2 (the "Tax-Related
          Covenants"), the Contributors shall be entitled to receive from the
          Operating Partnership as damages an amount equal to the aggregate
          federal income taxes and state income taxes (at a rate of 6%) incurred
          by the Contributors as a result thereof (and shall not be entitled to
          any "gross-up" with respect thereto). Any such federal and state
          income taxes shall be deemed to the amount of gain or income
          recognized by the Contributors (not in excess of the applicable
          Guaranteed Amount) multiplied by then the highest rate or rates (6% in
          the case of state income taxes) applicable to such gain or income for
          the year in which such gain or income its recognized. No effect shall
          be given in determining the amount of damages to the Contributors of
          their other taxable income, tax deductions, tax credits, tax carry
          forwards nor to any other of their tax benefits or tax attributes.

     1.5  Rights and Remedies of Contributors

          Notwithstanding any provision of this Agreement, Contributors agree
          that the sole and exclusive rights and remedies to which they may be
          entitled at law in equity for a breach of the Tax-Related Covenants by
          the Operating Partnership shall be for damages as determined pursuant
          to Paragraph 1.4, and Contributors shall not be entitled to pursue a
          claim for specific performance of the terms of the Tax-Related
          Covenants. If Contributors notify in writing Operating Partnership of
          a claim that Operating Partnership has breached or violated any of the
          Tax-Related Covenants, Operating Partnership and Contributors agree to
          negotiate in good faith to resolve any disagreements regarding any
          such breach or violation. If any such disagreement cannot be resolved
          by Operating Partnership and Contributors within 30 days after receipt
          by Operating Partnership of the notice in accordance with the
          preceding sentence, Operating Partnership and Contributors shall
          jointly retain a nationally recognized independent public accounting
          firm (an "Accounting Firm") to act as an arbitrator to resolve as
          expeditiously as possible all points of any such disagreement
          (including, without limitation, whether a breach by Operating
          Partnership of any Tax-Related Covenants has occurred and, if so, the
          amount of damages that the Contributors are entitled to as a result
          thereof, determined as set forth in Paragraph 1.4). If the parties
          cannot agree on an Accounting Firm, each of Contributors and Operating
          Partnership shall retain an Accounting Firm, and the Accounting Firm
          selected by Operating Partnership and the Accounting Firm selected by
          Contributors shall jointly retain an Accounting Firm. If the two
          Accounting Firms cannot agree upon a third Accounting Firm within 30
          days, such matter shall be referred to a court of competent
          jurisdiction to select the third Accounting Firm. The Accounting Firms
          shall be instructed to resolve as expeditiously as possible all points
          of any such disagreement (including without limitation, whether a
          breach by Operating Partnership of any Tax-Related Covenants has
          occurred and, if so, the amount of damages that the Contributors are
          entitled to as a result thereof, determined as set forth in Paragraph
          1.4).

<PAGE>

          All determinations made by the Accounting Firm or the Accounting
          Firms, as the case may be, with respect to the resolution of any
          breach or violation of the Tax-Related Covenants shall be final,
          conclusive and binding on Operating Partnership and Contributors. The
          fees and expenses of any Accounting Firms incurred in connection with
          any such determination shall be shared equally by Operating
          Partnership and Contributors. The rights and remedies of Contributors
          set forth in this Paragraph 1.5 shall be available to each Contributor
          individually.

     1.6  Expenses

          Each party hereto shall pay its own expenses incident to this
          Agreement and the transactions contemplated hereunder, including all
          legal and accounting fees and disbursements

     1.7  Assignment

          No party hereto shall assign its rights and/or obligations under this
          Agreement, in whole or in part, whether by operation of law or
          otherwise, without the prior written consent of the other parties
          hereto. Notwithstanding anything to the contrary in the preceding
          sentence, at any time after the Closing Date, Operating Partnership
          may assign its rights and/or obligations under this Agreement to an
          affiliate, or any other person or entity in connection with a merger,
          consolidation, sale or contribution of all or substantially all of its
          assets, or other similar corporate transaction; provided, that no
          assignment pursuant to the preceding clause shall release Operating
          Partnership from its liabilities and obligations hereunder.

     1.8  Entire Agreement, Amendment

          This Agreement, including the Schedules and other documents referred
          to herein or furnished pursuant hereto, together with the Contribution
          Agreement and the exhibits and other documents referred to therein of
          furnished pursuant thereto, constitute the entire agreement among the
          parties hereto with respect to the transactions contemplated herein,
          and supersede all prior oral or written agreements, commitments or
          understandings with respect to the matters provided for herein. No
          amendment, modifications or discharge of this agreement shall be valid
          or binding unless set forth in writing and duly executed and delivered
          by the party against whom enforcement of the amendment, modifications,
          or discharge is sought.

     1.9  Waiver

          No delay or failure on the part of any party hereto in exercising any
          right, power or privilege under the Agreement or under any other
          documents furnished in connection with or pursuant to this Agreement
          shall impair and such right, power or privilege or be construed as a
          waiver of any default or any acquiescence therein. No single or
          partial exercise of any such right, power or privilege shall preclude
          the further exercise of such right, power or privilege, or the
          exercise of any other right, power or privilege. No

<PAGE>

          waiver shall be valid against any part hereto unless made in writing
          and signed by the party against whom enforcement of such waiver is
          sought and then only to the extent expressly specified therein.

     1.10 Severability

          If any part of any provision of this Agreement or any other agreement
          or document gives pursuant to or in connection with this Agreement
          shall be invalid or unenforceable in any respect, such part shall be
          ineffective to the extent of such invalidity or enforceability only,
          without in any way affecting the remaining parts of such provision or
          the remaining provisions of this agreement.

     1.11 Governing Law

          This Agreement, the rights and obligations of the parties hereto, and
          any claim or disputes relating thereto, shall be governed by and
          construed in accordance with the laws of the State of Maryland
          (excluding the choice of law rules thereof).

     1.12 Notices

          All notices, demands, requests, or other communications which may be
          or are required to be given, served, or sent by any party to any party
          pursuant to this Agreement shall be in writing and shall be hand
          delivered, sent by overnight courier or mailed by first-class,
          registered or certified mail, return receipt requested, postage
          prepaid, or transmitted by facsimile, telegram, telecopy or telex,
          addressed as follows:

          (i)  If to any Contributor:

               Clayton, Williams & Sherwood, Inc.
               Attn:      Steven J. Sherwood
                          Byron L. Williams
                          800 Newport Center Drive
                          Newport Beach, CA 92660
               Facsimile: (714) 630-2701

               With a copy to

               Riordon & McKinzie
               Michael P. Whalen
               695 Town Center Drive, Suite 1500
               Costa Mesa, CA 92626
               Facsimile: (714) 549-3244

<PAGE>

          (ii) If to Operating Partnership

               CWS Communities LP
               c/o CWS Communities Trust
               11 South LaSalle Street
               Chicago, IL 60603
               Attn: Caroline S. McBride
               Facsimile: (312) 345-5888

               With copy to:

               Mayer, Brown & Platt
               Attn: William Levy
               190 South LaSalle Street
               Chicago, IL 60603
               Facsimile: (312) 701-7711

          Each additional party may designate by notice in writing a new address
          to which any notice, demand, request or communication may thereafter
          be so given, served or sent. Each notice, demand, request or
          communication which shall be hand delivered, sent, mailed faxed,
          telecopied or telexed in the manner described above, or which shall be
          delivered to a telegraph company, shall be deemed sufficiently given,
          served, sent, received or delivered for all purposes at such time as
          it is delivered to the addressee (with return receipt, the delivery
          receipt, the confirmation receipt (with respect to a facsimile), or
          (with respect to a telecopy or telex) the answerback being deemed
          conclusive, but not exclusive, evidence of such delivery) or at such
          time as delivery is refused by the addressee upon presentation.

     1.13 Headings

          Section headings contained in this Agreement are inserted for
          convenience of reference only, shall not be deemed to be a part of
          this Agreement for any purpose, and shall not in any way define or
          affect the meaning, construction or scope of any of the provisions
          hereof.

     1.14 Execution in Counterparts

          To facilitate execution, this Agreement may be executed in as many
          counterparts as may be required. It shall not be necessary that the
          signature of, or on behalf of, each party, or that the signatures of
          all persons required to bind any party, appear on each counterpart;
          but it shall be sufficient that the signature of, or on behalf of,
          each party, or that the signatures of that persons required to bind
          any party, appear on one or more of the counterparts. All counterparts
          shall collectively constitute a single agreement. It shall not be
          necessary in making proof of this Agreement to produce or account for
          more than

<PAGE>

          a number of counterparts containing the respective signatures of, or
          on behalf of, all of the parties hereto.

     1.15 Attorneys' Fees

          Should either party employ attorneys to enforce any of the provisions
          hereof, the party against whom any final judgment is entered agrees to
          pay the prevailing party all reasonable costs, charges and expenses,
          including reasonable attorneys' fees, expended or incurred by the
          prevailing party in connection therewith.

                                                  {Signature pages to follow}

<PAGE>

                                  CWS COMMUNTITIES LP
                                  By: CWS Communities Trust, Its general partner


                                  By:
                                     -------------------------------------------
                                  Name:
                                       -----------------------------------------
                                  Title:
                                        ----------------------------------------


                                  THE STEVEN SHERWOOD TRUST DATED
                                     SEPTEMBER 8, 1994


                                  By:
                                     -------------------------------------------
                                           Steven J. Sherwood, Trustee


                                  CORAL CAY, LLC


                                  By:
                                     -------------------------------------------
                                       Byron L. Williams, Managing Member


                                  ----------------------------------------------
                                  JAMES L. CLAYTON, INDIVIDUALLY


                                  TANA J. SHERWOOD TRUST DATED
                                  APRIL 9, 1992


                                  By:
                                     -------------------------------------------
                                       Tana J. Sherwood, Turstee


                                  ----------------------------------------------
                                  JOSEPH H. SHERWOOD III, JTWROS


                                  ----------------------------------------------
                                  LAURA G. SHERWOOD, JTWROS


                                  CURTIS LIVING TRUST


                                  By:
                                     -------------------------------------------
                                       Paul D. Curtis, Trustee

                                  By:
                                     -------------------------------------------
                                       Lori E. Curtis, Trustee


                                  WALDO NEIKIRK TRUST U/T/D DATED
                                  JUNE 20, 1994


                                  By:
                                     -------------------------------------------
                                       W. W. Neikirk, Trustee

<PAGE>

                                  KUK FAMILY TRUST


                                  By:
                                     -------------------------------------------
                                       Thomas J. Kuk, Trustee


                                  By:
                                     -------------------------------------------
                                       Ronda R. Blehm-kuk, Trustee


                                  CLAYTON, WILLIAMS & SHERWOOD
                                  FIANACAIL GROUP 80


                                  By:
                                     -------------------------------------------
                                  Name:
                                       -----------------------------------------
                                  Title:
                                        ----------------------------------------

<PAGE>

                                   SCHEDULE A
                             CONTRIBUTED PROPERTIES

Contributed Property
--------------------

Arlington Lakeside

Grand Place

Northwood

Stone Mountain

Woodlands of Kennesaw

<PAGE>

                                   SCHEDULE B
                                  EXISTING DEBT

Contributed Property                    Existing Debt
---------------------                   -------------

Arlington Lakeside                        $3,046,521

Grand Place                               $3,800,840

Woodlands of Kennesaw                     $4,175,940

Stone Mountain                            $4,257,884

Northwood                                 $5,001,032

<PAGE>

                                   SCHEDULE C
                               GUARANTEED AMOUNTS

Contributed Property                    Guaranteed Amounts
---------------------                   ------------------

Arlington Lakeside                          $3,224,464

Grand Place                                 $3,791,840

Woodlands of Kennesaw                       $4,179,304

Stone Mountain                              $4,257,884

Northwood                                   $4,991,250

<PAGE>

                                FIRST SUPPLEMENT
                            TO TAX RELATED AGREEMENT

     THIS FIRST SUPPLEMENT TO TAX RELATED AGREEMENT ("First Supplement") dated
effective as of April 1, 1999, is entered into by CWS COMMUNTIIES LP, a Delaware
limited partnership (the "Operating Partnership"), at the request and for the
benefits of the Contributors (defined below).

                                    RECITALS

          A.   Operating Partnership and various other individuals an entities
               (each a "Contributor") entered into that certain Tax-Related
               Agreement dated March 6, 1998 (the "Tax Related Agreement") All
               initially-capitalized terms not otherwise defined herein shall
               have the meanings set forth in the Tax Related Agreement unless
               the context clearly indicates otherwise.

          B.   Operating Partnership and the Contributors each desire to
               supplement the Tax Related Agreement by adding two properties as
               Contributed Properties.

          NOW THEREFORE, for good and valuable consideration, the receipt and
          sufficiency of which are hereby acknowledge, the undersigned hereby
          agrees as follows:

                                    AGREEMENT

          1.   Supplement to Schedule A to the Tax Related Agreement. Schedule A
               of the Tax Related Agreement is hereby supplemented to include
               the following properties as "Contributed Properties," and the
               Operating Partnership agrees to hold, encumber, and dispose of
               such properties as Contributed Properties according to the terms
               and conditions of the Tax Related Agreement:

               (a)  The manufactured home community commonly known as Oakcrest
                    Point located in San Antonio, Texas; and

               (b)  The manufactured home community commonly known as Misty
                    Winds located in Corpus Christi, Texas.

          2.   Supplement to Schedule B to the Tax Related Agreement. Schedule B
               of the Tax Related Agreement is hereby supplemented to include
               the following existing debt for the new Contributed Properties:

                    Contributed Property:   Existing Debt
                    ---------------------   -------------

                    Oakcrest Point            $4,100,000

                    Misty Winds               $2,700,000

<PAGE>

          3.   Supplement to Schedule C to the Tax Related Agreement. Schedule C
               of the Tax Related Agreement is hereby supplemented to include
               the following guaranteed amounts for the new Contributed
               Properties:

                    Contributed Property:   Guaranteed Amount
                    ---------------------   -----------------

                    Oakcrest Point              $2,000,000

                    Misty Winds                 $1,600,000

          4.   Counterparts. This First Supplement may be executed in any number
               of counterparts, each of which shall be deemed an original, but
               all of which when taken together shall constitute one and the
               same instrument. Each counterpart may be delivered by facsimile
               transmission. The signature page of any counterpart may be
               detached therefrom without impairing the legal effect of the
               signature(s) thereon provided such signature page is attached to
               any other counterpart identical thereto.

<PAGE>

     IN WITNESS WHEREOF, Operating Partnership has executed this First
     Supplement as of the day and year first above written.


                                  CWS COMMUNITIES LP

                                  By: CWS Communities Trust, its general partner


                                  By:
                                     -------------------------------------------
                                  Name: Carl D. Watkins
                                  Title: Vice President