The premium is charged at the stated annual rate on the original loan amount, which is how insurers commonly price it. The statutory dates are those in the Homeowners Protection Act and apply to borrower-paid mortgage insurance on a conventional first mortgage for a principal residence; lender-paid insurance and FHA insurance sit outside them. A down payment of 20% or more on a conventional loan needs no insurance and returns zero months. Property value is held at the purchase price throughout, because that is the value the statute measures both thresholds against.