What is the difference between mortgage pre-qualification and pre-approval?

Pre-qualification is an informal estimate of how much you might borrow based on self-reported income and debt information — no verification is done. Pre-approval is a more rigorous process where the lender verifies your income, assets, credit report, and employment, then commits (conditionally) to a specific loan amount. Sellers take pre-approval letters much more seriously than pre-qualification. Pre-approval typically involves a hard credit inquiry and is valid for 60–90 days. Getting pre-approved before house hunting puts you in a much stronger negotiating position.