Another option to sell a business with an SBA loan is for the buyer to assume the loan. SBA loans are fully assumable with SBA approval.What Is Required to Assume an SBA 504 Loan? Assumption of Loan Requirement Letter for disaster loan servicing action request packages. About this document and download. A mortgage assumption takes place when the buyer takes over the seller's existing mortgage at closing in lieu of getting a new loan. Mortgage assumption allows a buyer to take on the original loan balance at the original terms, but it doesn't account for any home equity the seller has built. Most SBA lenders allow buyers to make payments on the seller financing, so long as they do not default on the SBA loan. Verify Loan Assumability. The first step is to reach your mortgage contract and confirm that loan assumption is possible.