Mortgage preapproval helps determine how much you can borrow and strengthens your home offer. It typically takes from the same day up to 10 business days, depending on document readiness and financial complexity. Preapproval requires verified financial documents, unlike pre-qualification, which is based on self-reported info. Preapprovals usually last 30 to 90 days and are essential before house hunting seriously. Self-employed buyers may need additional documentation.