An assumption clause in a mortgage contract allows a home's seller to pass responsibility for the existing mortgage to the new homebuyer. A mortgage assumption agreement is basically you coming in and saying sign this paperwork I'm still responsible for the mortgage.DEPOSIT INSURANCE CORPORATION, RECEIVER of FIRST REPUBLIC BANK,. This usually involves submitting financial documents such as income statements, credit reports, and bank statements. Two providers, Homepoint (no longer around) and Nationstar both offer a loan assumption as long as you can qualify for the loan individually. Mortgage assumptions where a buyer assumes the existing mortgage loan of a seller have fluctuated in popularity since the 1980s.