how long are pre approvals on mortgages good for
HSH Editors HSH.com. Since a preapproval letter is a conditional agreement of how much house you can afford, your mortgage preapproval is only good as long as the terms in the preapproval letter do not change.or example, your preapproval letter states that you qualify for given loan amount at a given interest rate. If mortgage rates rise, you will qualify for less; if mortgage rates fall, you can qualify for more.