For borrowers who are struggling to come up with a large down payment but have the income to qualify for a loan the Federal Housing Administration (FHA) offers FHA insurance to lenders to cover the loan thus encouraging them to loan to credit-worthy potential buyers. FHA buyers only need 3.5 percent as a down payment to get the maximum loan amount.
Mortgage lending limits vary by county and are determined by the local housing market with details spelled out in the National Housing Act. The limits of the loans for 2018 are in this chart. Basically, for San Diego County the upper limit is $649,750 for a single family home.