K Private mortgage insurance is often required by a lender when a buyer puts up less than 20 percent of the purchase price of a home for a down payment. The buyer pays the premium, though the lender is the one protected if the buyer defaults. The cost can be charged upfront or spread over the life of the loan. K A monthly expense that in some cases can be dropped after the loan-to-value ratio for a property reaches 80 percent. That happens when the owner’s equity goes up, either because he or she has paid down the mortgage or because the home’s value has appreciated. K A different kind of insurance from that on loans backed by the Federal Housing Administration and other government agencies, thus the “private” in the name. Premiums on FHA mortgages last for the life of the loan. K A product that many homeowners have complained that they have had difficulty canceling once they met the minimum equity requirements. K An expense many cash-strapped borrowers have avoided in recent years using 80/20 or 80/10/5 loans. Under those loans, second mortgages are “piggybacked” onto the primary mortgages. K An option that has become more attractive now that interest rates on some adjustablerate second mortgage loans have risen sharply. K A cost that home buyers with incomes under $100,000 can now fully deduct on their income taxes — similar to the way mortgage interest is deducted — due to a law that went into effect this year. That law was effective with insurance on loans closed on or after Jan. 1; so far, it has not been extended to cover insurance written after this year.