Assumable 101
What Is the Downpayment Gap on a Mortgage Assumption?
By David Golovin · October 6, 2026 · 2 min read
When you assume a mortgage, you take over the existing loan. The downpayment gap is the difference between that balance and the sale price.
Example: $425,000 home, $248,000 remaining balance
Source: Roots live inventory, estimated average gap on active assumable listings
Options to cover the gap
Buyers cover the gap with cash, a second mortgage at market rates, seller concessions, or gift funds. Estimated average gap on active Roots assumable listings: $181,208.
How much can you save?
Estimated Assumption Savings Calculator
Home price
Assumable loan balance
Assumable interest rate
Current market rate
Estimated results
All figures are estimates based on a 30-year fixed term and standard amortization. Market loan assumes 20% down on the home price. Downpayment gap is the difference between the sale price and the assumable loan balance and may be financed separately. This calculator is for educational purposes only. Roots is a licensed brokerage, not a lender. All loan approvals and credit decisions are made by the lender.
FAQ
What is the downpayment gap on a mortgage assumption?
The gap is the difference between the sale price and the remaining loan balance. A $400,000 home with a $230,000 balance has a $170,000 gap the buyer covers at closing.
Can you get a second mortgage to cover the downpayment gap?
Some lenders offer second mortgages to help bridge assumption gaps. The servicer on the assumed loan and the VA or FHA insurer set the rules on what is allowed.
Do all assumable mortgages have a large downpayment gap?
Not always. A seller who bought recently and has little equity may have a small gap. The gap grows as the seller builds equity.