Private Mortgage Insurance, or PMI, is an added insurance policy for homeowners who have a down payment that is less than 20%. PMI protects the lender if the borrower is unable to pay their mortgage. This insurance is not forever. It will either end automatically when a mortgage’s principal balance reaches 78% of the original appraised value of the home or the borrower can ask the lender for a new appraisal to validate that they have built at least 20% equity in their home.