<PAGE>
                                                                    Exhibit 10.1

                            CUMMINGS PROPERTIES, LLC
                                 STANDARD FORM

                                                                  08030417-DGC-C
                                LEASE EXTENSION

      In connection with a lease currently in effect between the parties at 10-M
Commerce Way , Woburn , Massachusetts, executed on November 3, 1998 and
terminating December 14, 2003 , and in consideration of the mutual benefits to
be derived herefrom, Cummings Properties, LLC, LESSOR, and MicroFinancial
Incorporated , LESSEE, hereby agree, effective December 15, 2003 , to amend said
lease as follows:

1.    The lease is hereby extended for an additional term of two (2) years and
      one-half (1/2) month ending at noon on December 30, 2005 .

2.    Base rent is hereby changed to five hundred eighty four thousand seven
      hundred ninety two (584,792) dollars per year or $ 48,732.66 per month.

3.    The base month from which to determine the amount of each annual increase
      * in the "Cost of Living" shall be **November 2004 , which figure shall be
      compared with the figure for November 2004 , and each November thereafter
      to determine the percentage increase * (if any) in the base rent to be
      paid during the following calendar year.
      *or decrease      **January

                        [THIS PARAGRAPH DOES NOT APPLY]
4.    Upon execution of this Lease Extension, the security deposit shall be
      increased by $ from $ to a new total of $ . LESSEE shall pay this increase
      upon LESSEE's execution of this Lease Extension.

                        [THIS PARAGRAPH DOES NOT APPLY]
5.    The lease, including all terms, conditions, escalations, etc. shall be
      automatically extended for additional successive periods of two (2) years
      each unless LESSOR or LESSEE shall serve written notice, either party to
      the other, of either party's desire not to so extend the lease. The time
      for serving such written notice shall be not more than twelve months or
      less than six months prior to the expiration of the then current lease
      period. Time is of the essence.

6.    Notwithstanding Section 20 of the lease, in the event the entire balance
      of rent due under the lease becomes due and payable as liquidated damages,
      said amount shall be discounted to its net present value as of the date of
      LESSOR's notice of default, using the published prime rate then in effect.
      Furthermore, LESSEE's covenants under the lease shall be independent of
      LESSOR's covenants, and LESSOR's failure to perform any of its covenants
      under the lease, including a covenant constituting a significant
      inducement to LESSEE to enter into the lease, shall not excuse the payment
      of rent or any other charges by LESSEE or allow LESSEE to terminate the
      lease.

7.    In the event either party has employed a real estate broker, tenant
      representative, or other third party on its behalf in connection with this
      Lease Extension and/or any further extension, renewal, or expansion of the
      lease, then payment of any and all fees or commissions shall be the sole
      responsibility of the party engaging any such broker, representative, or
      third party. LESSEE and LESSOR agree that the party who so engages any
      broker, representative, or other third party shall indemnify the other
      against any and all claims for any such fees or commissions.
      Notwithstanding the above, LESSOR agrees to pay a brokerage commission of
      $26,315.64 on LESSEE's behalf to Brian T. Hines of Trammell Crow Company
      on account of this Lease Extension. LESSEE warrants that this is the total
      commission to be paid by LESSOR on account of this Lease Extension, and
      shall indemnify and hold LESSOR harmless against any other commission
      arising out of this Lease Extension.

8.    To the extent any inconsistency exists between this Lease Extension and
      the lease, including any prior amendments, the conditions contained herein
      shall control and supersede any earlier provisions. Neither the submission
      of this Lease Extension, nor the prospective acceptance of any increase in
      the security deposit, shall constitute a reservation of or option for the
      leased premises, it being expressly understood and agreed that this Lease
      Extension shall not bind either party in any manner whatsoever until it
      has been executed by both parties.

9.    * During the extended lease term as described above, the base from which
      to determine the amount of any increase in real estate taxes pursuant to
      Section 4 of the lease is hereby changed to the rate and the assessment in
      effect as of July 1, 2003.

10.   * Leasecomm Corporation (a MA corp.) is hereby added as LESSEE in addition
      to MicroFinancial Incorporated. "LESSEE" as used in the lease, including
      any amendment thereto, shall refer to both entities, and their
      responsibility shall be joint and several pursuant to Section 30 of the
      lease. The party added herein as LESSEE shall, upon its execution of this
      Lease Extension, supply LESSOR with a certificate of insurance in the
      amount of $1,000,000 naming LESSOR and the owner of the building (OWNER)
      as additional insureds. LESSOR and OWNER shall be included as additional
      insureds using standard endorsement ISO Form CG 20 26 11 85 or another
      similar form specifically approved in advance by LESSOR.


                                                                    /s/   LESSOR
                                                                   -----
                                                                    /s/   LESSEE
                                                                   -----
                                                                    /s/   LESSEE
                                                                   -----
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                                LEASE EXTENSION
                                  (CONTINUED)

11.   Notwithstanding anything in the lease to the contrary, in no case may
      LESSEE assign the lease or sublet the leased premises to any current or
      prospective tenant of LESSOR, or any affiliate of such current or
      prospective tenant. In the event LESSOR approves a sublease or assignment
      of the lease, LESSEE shall pay LESSOR on or before the first of each month
      during the period of the sublease or assignment, 50 percent of any amount
      by which the payments due to LESSEE under the sublease or assignment
      exceed the rent payment due from LESSEE to LESSOR for that month, after
      agreed upon deductions for brokerage fees, tenant improvements allowances
      and attorney fees (if any). Such amount shall, however, be calculated on a
      proportionate basis in the case of a sublease of only a portion of the
      leased premises. The provisions of Section 11 of the lease shall govern
      subleases and assignments in all other respects. For the purpose of this
      section "prospective tenant" shall mean any entity or individual that
      during the previous 12 months, has been in contact with LESSOR with
      respect to leasing space in a property owned or managed by LESSOR, either
      directly or through an agent or broker.

12.   * LESSOR represents that Cummings Properties, LLC has succeeded to all
      interests of Cummings Properties Management, Inc. as LESSOR.




      All other terms, conditions and covenants of the lease shall continue to
apply. In Witness Whereof, LESSOR and LESSEE have hereunto set their hands and
common seals this 16th day of September ,2003.

LESSOR: CUMMINGS PROPERTIES, LLC          LESSEE: MICROFINANCIAL INCORPORATED

  By: /s/ Douglas Stephenson                By: /s/ Richard F. Latour
      --------------------------------          --------------------------------
                       Duly Authorized                           Duly Authorized

                                            Print Name: /s/ Richard F. Latour
                                                        ------------------------

                                          LESSEE: LEASECOMM CORPORATION

                                            By: /s/ Richard F. Latour
                                                --------------------------------
                                                                 Duly Authorized

                                            Print Name: /s/ Richard F. Latour
                                                        ------------------------

06/2003