To change a mortgage borrower, the primary method is refinancing or a loan modification. Refinancing involves securing a new loan to replace the existing one, allowing the original borrower to be removed and a new borrower to assume the obligation. The process requires: 1) Lender approval, 2) submission of updated financial documents (e.g., credit reports, tax returns), 3) reunderwriting, and 4) completion of closing procedures. If the mortgage is held in a trust or securitized, additional steps like investor consent may apply. For co-borrowers, a "release" can sometimes be negotiated if the original borrower meets certain criteria.

The necessity of this process stems from legal and financial constraints. U.S. mortgage contracts typically bind borrowers indefinitely, and unilateral changes without lender approval can violate terms. From 2020 Q1 data, 76% of refinancers sought to replace primary borrowers due to financial stress or improved creditworthiness, per the Mortgage Bankers Association. Refinancing costs average $5,000–$6,000 (Bankrate, 2023), including appraisal ($500–$1,000), title search ($400–$600), and legal fees ($300–$800). Legal challenges arise when original borrowers attempt to transfer without lender consent, as seen in 2022 California courts where 43% of cases involved improperly altered loans (California Law Review, 2023). This underscores the importance of formalizing changes through structured refinancing to avoid default risks and ensure regulatory compliance.