Rate Lock Extension Fee Calculator

If your mortgage closing gets delayed past the rate-lock expiration, you face two choices: pay a lock extension fee to keep your locked rate, or float to a new lock at today's market rate. The math depends on how much rates have moved since you locked. This calculator compares the one-time extension fee against the lifetime interest premium of re-locking at a higher rate.

Rate Lock Extension Fees — What Lenders Charge

Standard extension fees: 0.125%-0.25% of the loan amount per 15 days. So a $400K loan extending 30 days costs $1,000-2,000. Some lenders offer one free 7-15 day extension; others charge from day one of overrun. Always ask what extension policy is included BEFORE you lock — get it in writing. If the delay is the lender's fault (slow underwriting, appraisal scheduling issues), push for a free extension under the lender's quality-of-service guarantee.

When to Pay the Extension Fee

Pay the extension fee when current rates are HIGHER than your locked rate. The extension fee is one-time; the re-lock rate premium is paid every month for 30 years. Typically the math overwhelmingly favors extension if rates have moved up even 0.125% since you locked. For example: $400K loan, locked at 6.25%, current rate 6.5%, extension fee 0.25% ($1,000): re-locking adds $66/month forever = $23,760 over 30 years. Extension is a no-brainer here.

When to Decline the Extension and Float Down

Decline extension and float to current market rate when rates have DROPPED since you locked. Most lock agreements include a 'float-down' provision allowing one-time rate reset to current market for a small fee (usually 0.125%) if rates have dropped 0.25%+ since lock. Without float-down, you can simply let the lock expire and re-lock at current market. The risk: rates rebound before you close. Float-down lets you capture rate drops without the bounce risk.

Last updated May 2026. Sources: CFPB.