Credit glossary
Desktop Underwriter (DU)
Fannie Mae's automated underwriting system, which lenders use to evaluate conventional mortgage applications against Fannie Mae's rules.
DU reads your tri-merge credit report along with income, assets and loan details, then returns a recommendation. For casefiles created on or after November 16, 2025, DU no longer applies a minimum credit score, though manually underwritten Fannie Mae loans still need 620 for fixed rates and 640 for ARMs, and many lenders keep their own floor. DU has used trended credit data in its risk assessment since Version 10.0 in 2016.
DU is also where disputes collide with mortgages. If a loan doesn't approve with disputed tradelines included, DU reruns it without them and the lender must investigate. If the disputed accounts are yours and accurate, the loan can't be delivered as a DU loan. With multiple borrowers, Fannie Mae's guide describes using the average of the borrowers' median scores.
Guides that go deeper
- Credit score for a conventional loan after Fannie Mae dropped 620Fannie Mae's automated underwriting no longer requires a 620 score, but manual loans, lender overlays and pricing still do. What changed and what didn't.
- What not to dispute on your credit report before a mortgageDisputing accurate items rarely helps, and open disputes can stall a mortgage. How Fannie Mae and FHA treat disputed accounts, and what to do instead.
- Trended data: when your balance history starts to countFICO 10T and VantageScore 4.0 read about two years of balance history, not one month. How far back each looks, who uses them, and what it changes for you.
Sources
- DU Version 12.0 November 15, 2025 Release Notes, Fannie Mae
- B3-5.1-01, General Requirements for Credit Scores, Fannie Mae Selling Guide
- Desktop Originator/Desktop Underwriter Release Notes, DU Version 10.0, Fannie Mae
- B3-5.3-09, DU Credit Report Analysis, Fannie Mae Selling Guide
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