Novation: What's the difference? A novation is a legal instrument used to replace one obligation or party with another in a contract.An assignment and assumption agreement transfers one party's rights and obligations to a third party. In an assignment, the wholesaler assigns the benefits of the original contract to another party and the original contract remains intact. Edit, sign, and share assumption agreement online. No need to install software, just go to DocHub, and sign up instantly and for free.