Tip,I am a Realtor in Virginia (not sure whether you are purchasing actually in D.C. or Northern Virginia). In Virginia, our Purchase Agreement requires that the buyer name a lender he or she is going to use. This is done so the seller (while not directing who you MUST use) can veto your selection of lenders, should it be an unknown company, a company with known problems, or for other reasons. If you have not made your final selection as to which lender you will use...my suggestions to buyers is that we put more than one lender in the Purchase Agreement, leaving you the ability to make sure you are pleased with rates, terms, and yes -- even compatability, etc, once you have made your home selection clear to the lender(s). You may be required to submit letters from each of these lenders you have narrowed your selections to, when making your offer. If after the offer is ratified by the seller, you decide to pursue a lender outside of those you entered in the Purchase Agreement...you will have to have the selection approved (in writing) by the seller before switching.