If you are thinking about buying a home and want to start looking, you will need to get a copy of your mortgage pre-approval letter to your Realtor. This is important because most homes listed on the Houston Multiple Listing Service (MLS) require such a letter accompany the offer being submitted to purchase the home. This protects the seller, as he is taking his home off of the market for the proposed buyer. Without some indication the buyer will qualify for the loan, the seller will not want to take his home off the market for you. A pre-approval is a commitment from the mortgage company. A pre-qualification letter is different. There is no commitment from the lender. That is why a pre-approval letter is necessary.