Can a New York landlord raise rent more than once a year?

It depends on the tenancy type and any applicable rent control. On a month-to-month tenancy, a New York landlord can technically issue multiple rent increases in one year, each with the proper notice (New York uses a tenure-based notice ladder at RPL 226-c: 30 days for tenancies under 1 year, 60 days for 1-2 years, 90 days for 2+ years. Only triggers if the increase exceeds 5% or the landlord does not renew. Good Cause Eviction (Part HH 2024) caps increases at CPI + 5% or 10% max in NYC and opt-in municipalities, with exemptions for small owner-occupied buildings and new construction.). However, in jurisdictions with rent caps (California's AB 1482, Washington's HB 1217, New York's Good Cause coverage), the annual cap applies regardless of how many increase notices are issued. So even if a landlord delivers two increase notices in 12 months, the combined increase cannot exceed the statutory annual cap. On a fixed-term lease, no increase is permitted during the term unless the lease itself authorizes it, regardless of state. After the term ends, the landlord can issue an increase as part of the renewal offer.

Source: RPL 226-c (HSTPA 2019)