I’m assessing a New York 1-bed serviced apartment at $1,140,000, with expected rent of $4,490/month. That gives a headline gross yield of roughly 4.7%. The building appears sound, and I’m checking sold-price history, but financing could turn a marginal deal negative. My model includes vacancy, management, routine maintenance and a larger-repair reserve. Which local cost am I most likely understating—property tax, insurance, building charges or turnover—and what net yield would justify the risk for you?