In New York City, unless your lease says otherwise, you are not obligated to give the landlord advance notice of your plans to vacate, as long as you are out by the last day of the lease and leave a clean, empty apartment. If you happen to be a month-to-month tenant, then the last day of any such month is the end of your lease term. In either instance, whether your lease is yearly or monthly, if you're in the last month and you notify the landlord in the last few days that you don't intend to renew, you are not responsible for the following month's rent because you gave late notice. Sometimes an unscrupulous landlord will attempt to cheat a tenant for an additional month's rent, or more, for eleventh-hour notice of termination. If your landlord refuses to accept return of the keys, or tries to obstruct your surrender of the apartment, you should contact an experienced Landlord Tenant attorney immediately. In this instance, a whole series of complexities can arise which may require professional legal assistance to resolve.