Beyond the Guide: A Deep Dive into Mortgage Underwriting - VantageScore 4.0 Is Open to Every Fannie Mae Lender

On September 9, 2026, Fannie Mae’s Lender Letter LL-2026-06 made VantageScore 4.0 available to every approved lender without prior approval. This post walks through what the letter allows and requires, from the one-model-per-loan rule and three-bureau ordering to Special Feature Code 067. It also covers how the representative score still works and the defects QC reviews should look for.