Understanding the Reverse Mortgage Math

A Home Equity Conversion Mortgage (HECM) allows seniors to access their home equity without taking on a monthly payment. However, determining exactly how much cash you can access is complex. Lenders do not simply give you 100% of your home's value. The Reverse Mortgage Estimation Calculator models the FHA's algorithm to show you your true "Principal Limit"—the actual maximum amount the government will insure for your specific profile.

The Principal Limit Factor (PLF)

Your Principal Limit is calculated by multiplying your home's appraised value by a percentage known as the Principal Limit Factor (PLF). The PLF is determined by a matrix published by the Department of Housing and Urban Development (HUD), relying on two variables: the age of the youngest borrower and the Expected Interest Rate.

Age: The older you are, the higher your PLF. A 90-year-old might be allowed to borrow 60% of their home's value, while a 62-year-old might only be allowed to borrow 40%. The FHA assumes older borrowers have a shorter life expectancy, meaning the loan will accrue interest for fewer years before being repaid.

Interest Rates: When prevailing interest rates are low, the PLF goes up, allowing you to borrow more. When rates are high, the PLF drops significantly. This is because at high interest rates, the loan balance will grow rapidly through compound interest; the FHA must restrict initial borrowing to ensure the future loan balance doesn't vastly exceed the future home value.

Mandatory Payoffs and Upfront Costs

If your Principal Limit is $250,000, you do not immediately receive $250,000 in your bank account. FHA rules require that any existing liens on the property be paid off first. If you still owe $100,000 on your primary mortgage, those funds are automatically deducted from your Principal Limit to pay off the bank. This eliminates your monthly mortgage payment, but reduces your cash-in-hand.

Additionally, reverse mortgages carry high upfront costs. You must pay a 2% initial Mortgage Insurance Premium (MIP) to the FHA, an origination fee (capped at $6,000), and standard closing costs. These are typically financed into the loan, meaning they are deducted from your Principal Limit before you see the remaining "Net Available Funds."

The Rising Loan Balance

Because you are not making monthly payments, the interest and annual MIP (0.5%) are continually added to your loan balance. This results in negative amortization—your debt grows every month. As shown in the Equity Projection chart, over 10 to 15 years, the loan balance can grow substantially, consuming the remaining equity in the home unless the property appreciates at a very high rate.