2010 New York Code
RPP - Real Property
Article 7 - (220 - 238) Landlord and Tenant
226-B - Right to sublease or assign.

§  226-b.  Right  to  sublease or assign. 1. Unless a greater right to
  assign is conferred by the lease, a tenant renting a residence  may  not
  assign his lease without the written consent of the owner, which consent
  may  be  unconditionally  withheld without cause provided that the owner
  shall release the tenant from the lease upon request of the tenant  upon
  thirty  days  notice  if  the owner unreasonably withholds consent which
  release shall be the sole remedy of the tenant. If the owner  reasonably
  withholds consent, there shall be no assignment and the tenant shall not
  be released from the lease.
    2. (a) A tenant renting a residence pursuant to an existing lease in a
  dwelling  having  four or more residential units shall have the right to
  sublease his premises subject to the written consent of the landlord  in
  advance  of  the  subletting.  Such  consent  shall  not be unreasonably
  withheld.
    (b) The tenant shall inform the landlord of his intent to sublease  by
  mailing  a  notice  of  such  intent  by  certified mail, return receipt
  requested.  Such  request  shall  be  accompanied   by   the   following
  information: (i) the term of the sublease, (ii) the name of the proposed
  sublessee, (iii) the business and permanent home address of the proposed
  sublessee,  (iv)  the  tenant's  reason for subletting, (v) the tenant's
  address for the term of the sublease, (vi) the written  consent  of  any
  cotenant  or  guarantor  of  the lease, and (vii) a copy of the proposed
  sublease, to which a copy of the tenant's lease  shall  be  attached  if
  available,  acknowledged by the tenant and proposed subtenant as being a
  true copy of such sublease.
    (c) Within ten days after the mailing of such  request,  the  landlord
  may  ask  the  tenant  for  additional  information  as  will enable the
  landlord  to  determine  if  rejection  of   such   request   shall   be
  unreasonable.  Any  such request for additional information shall not be
  unduly burdensome.  Within thirty days after the mailing of the  request
  for  consent,  or  of the additional information reasonably asked for by
  the landlord, whichever is later, the landlord shall send  a  notice  to
  the  tenant  of  his  consent  or,  if  he does not consent, his reasons
  therefor. Landlord's failure to send such a notice shall be deemed to be
  a consent to the proposed subletting.  If  the  landlord  consents,  the
  premises  may  be  sublet in accordance with the request, but the tenant
  thereunder, shall nevertheless remain  liable  for  the  performance  of
  tenant's  obligations  under  said  lease.  If  the  landlord reasonably
  withholds consent, there shall be no subletting and the tenant shall not
  be released from the  lease.  If  the  landlord  unreasonably  withholds
  consent,  the  tenant  may sublet in accordance with the request and may
  recover the costs of the proceeding and attorneys fees if  it  is  found
  that the owner acted in bad faith by withholding consent.
    3.  The  provisions of this section shall apply to leases entered into
  or renewed before or after the effective date of this  section,  however
  they  shall  not apply to public housing and other units for which there
  are constitutional or statutory criteria covering admission thereto  nor
  to  a proprietary lease, viz.: a lease to, or held by, a tenant entitled
  thereto by reason of ownership of stock in a corporate owner of premises
  which operates the same on a cooperative basis.
    4. With respect to units covered by the  emergency  tenant  protection
  act  of  nineteen seventy-four or the rent stabilization law of nineteen
  hundred sixty-nine the exercise of the rights granted  by  this  section
  shall  be  subject  to  the  applicable provisions of such laws. Nothing
  contained in this section two hundred twenty-six-b shall  be  deemed  to
  affect  the  rights, if any, of any tenant subject to title Y of chapter
  51 of the administrative code of the city of New York or  the  emergency
  housing rent control law.

5.  Any sublet or assignment which does not comply with the provisions
  of this section shall  constitute  a  substantial  breach  of  lease  or
  tenancy.
    6.  Any provision of a lease or rental agreement purporting to waive a
  provision of this section is null and void.
    7. The provisions of this section except for items in paragraph (b) of
  subdivision two of this section not previously required, shall apply  to
  all  actions  and  proceedings  pending  on  the  effective date of this
  section.
    8. Nothing contained in this section shall be  deemed  to  prevent  or
  limit  the  right of a tenant to sell improvements to a unit pursuant to
  article seven-C of the multiple dwelling law.