You’ll apply for a mortgage once a seller accepts your offer for their home and both parties sign the purchase agreement. Before you begin searching for homes and making offers, you’ll need to obtain a preapproval for the mortgage. The preapproval process is very similar to the application process, and much of the information you provide for a preapproval transfers to your application when the time comes. Get preapproved when you’re ready to search for homes. Typically, a preapproval remains valid anywhere from 30 days to 90 days. If you haven’t found a home by that time, you might need to ask your lender to issue a new preapproval letter.