Mortgage prequalification is easier to obtain than mortgage pre-approval in NYC, requiring only a brief phone call with a mortgage broker to discuss basic financial information. A prequalification letter is a high-level estimate of what you can afford, while a pre-approval letter is necessary for making serious offers on properties. To get pre-approved, consult a trusted mortgage broker, preferably one familiar with NYC's market. Having a pre-approval letter enhances your credibility with real estate agents and sellers.