A foreclosure is a legal proceeding that is started by a lender after a home owner has failed to pay his/her mortgage. After a home owner has failed to make their payments on time (usually at least 90 days, but a lender does not have to wait before holding a borrower in default after even one missed payment), a lender will serve notice of default on the borrower as required by the loan documents (specifically the Mortgage in New York State).