Answer
Most contracts include a clause requiring that owners or managers be informed in advance of any kind of sub-lease. The law, however, makes it clear that owners or managers may not "unreasonably" withhold permission for a sub-lease. In other words, if the person to whom an apartment is to be sub-leased meets the same credit standards and other criteria that the original tenant met, it is not reasonable for the owner or manager to deny permission for the sub-lease. But if a tenant proceeds to sub-lease an apartment without having first obtained the consent of the owner or manager, in writing, even though the contract includes a clause that says such permission must be granted for any sub-lease, the sub-lease will be invalid.