Home > Personal > Personal Lending > Mortgage > Mortgage Resources > Glossary > Underlying Mortgage Underlying Mortgage November 9, 2021 Generally refers to the first mortgage when there is a wraparound mortgage.You Might Also Like: Family MattersPreparing Financially for a Baby Everyday MoneyBudget Friendly Ideas for Thanksgiving Everyday MoneySenior Discounts and Savings Everyday MoneyStarting an Emergency Savings Account Living QuartersQuestions to Ask Your Home Inspector