Automated Underwriting System (AUS) (AUS)
Direct definition
Software that evaluates a mortgage application against program guidelines and returns a preliminary decision.
Written by the Vabasso Mortgage Editorial Team · Reviewed against agency and federal sources · Read our editorial policy for how we research and review mortgage content
Plain-English explanation
An AUS pulls credit, applies program rules, and delivers a recommendation like Approve/Eligible along with a list of documentation the underwriter must verify. Fannie Mae's DU and Freddie Mac's LP are the most common systems.
Why it matters
AUS findings shape what you'll need to document and how flexible the file can be on things like DTI, reserves, and appraisal type.
Where you may see it
- Underwriting conditions
- Pre-approval letter
- Loan application
A real-world example
Educational and illustrative only
A common misunderstanding
An AUS approval is not a final loan approval — it's a preliminary recommendation that still requires document verification.
Ask Vabasso AI
- Author
- Vabasso Mortgage Editorial Team
- Reviewed by
- Vabasso Mortgage Licensed Advisory Team
- Last reviewed
- July 30, 2026