New York City has it's own unique landlord/tenant laws, and many buildings are rent-controlled. Rent-controlled buildings must adhere to specific guidelines regarding how much rent can be increased and when. Tenants in rent-controlled buildings typically sign leases, as rent terms are important. However, even tenants in rent-controlled apartments with oral leases are entitled to appropriate notice regarding rent increases.
In New York City, oral leases are recognized as valid, and by operation of law, the existence of an oral lease creates a month-to-month tenancy. Oral leases for more than one year are required to be in writing. Regardless, if you have an oral lease, you can't move out without notice simply because the lease isn't in writing.
In New York City and throughout the state, unwritten leases are binding, provided they don't encompass a period that exceeds one year. When an oral lease goes beyond one year, the lease is required to be in writing to satisfy the "statute of frauds." Tenants who agree to a one-year, oral lease are considered to have a month-to-month tenancy.
When a landlord accepts rent without a written lease, the acceptance gives rise to a month-to-month tenancy. This means that both the landlord and the tenant are required to give each other 30 days' notice before terminating the lease. In New York City, 30 days' notice must be in writing; this applies to the landlord's notice and the tenant's notice.
If you have an oral lease, and you live in New York City, you owe your landlord 30 days' notice before moving out. If you move out without notice, your landlord can sue you for unpaid rent. It's important to note, however, that in the absence of a written lease, your landlord likely can't sue you for much more than one months' rent if you fail to give notice. This is, of course, unless your landlord can prove your oral lease was for a term of several months.