Fannie Mae DUS | 2026-08-31

Streamlined Treasury Lock Deals Need a Date Owner

Fannie Mae's August 2026 Streamlined Treasury Lock update turns rate-lock timing into a practical closing-calendar item.

Fannie Mae's Lender Letters page lists Lender Letter 26-07, dated August 18, 2026, as a loan-document update for Mortgage Loans with the Streamlined Treasury Lock feature. The letter states that the updates may be used immediately and must be used on or after August 20, 2026 for any Mortgage Loan with that feature.

The letter also creates Form 6430.STLA, the Streamlined Treasury Lock Agreement. Fannie Mae describes it as available only for fixed-rate executions when the borrower wants to lock the index and hold the spread before entering into a rate lock for the full interest rate. On or before the expiration of the Streamlined Treasury Lock Agreement, the borrower must enter into a Streamlined Rate Lock Agreement or Standard Rate Lock Agreement with the lender.

For borrower-side closing counsel, the legal checklist should not treat that timing as only a capital-markets item. Intake should identify whether the deal uses Streamlined Treasury Lock, who owns the expiration date, which rate-lock agreement is expected next, and whether execution authority, certificates, consents, or signature logistics need to be ready before the rate-lock step.

A clean DUS closing calendar should pair document-version control with deadline control. The file should show the applicable form set, the treasury-lock expiration date, the next required rate-lock agreement, the responsible contact, and any downstream effect on loan document circulation or closing conditions. This note is informational only and is not legal advice for any specific transaction.