Private Mortgage Insurance (PMI) is a type of insurance that protects the lender in case the borrower is unable to pay back the loan. It is typically required if the borrower is making a down payment of less than 20% of the purchase price. The cost of PMI varies, but it typically ranges from $30 to $70 per month per $100,000 borrowed. Homeowners Protection Act requires lenders to stop charging PMI premiums once the borrower has accumulated 22% of equity in their home.