We will soon begin accepting online loan applications. Is it necessary to post some sort of language on our website that we will only accept applications within our market area? Otherwise, I am afraid we will get applications that we do not want and end up wasting time and energy on loans we don't intend on making.

Consider setting it up this way:
1. Top level page(s) should promote credit products and contain "click here for more information" links or buttons. Pay attention to TIL trigger terms & provide full advertising disclosures when necessary.
2. Upon clicking, inquirer receives a page explaining your market area and any other automatic disqualifiers such as prior bankruptcy and under 18. You may want to present these standards as check boxes and require inquirers to provide favorable responses to each of these critical questions in order to advance to the first page of the online application.
3. Throughout this process, your focus should be "how we will accept your application", not "will you be denied." Explain that the online application will not be appropriate for all applicants and invite inquirers to contact a lender at one of your branches if they choose not to apply online.
4. It is not "discouragement on a prohibited basis" to announce your most basic qualifications and leave it to the inquirer to decide how to proceed. If the inquirer aborts the online application process and fails to call a branch, that is neither discrimination nor adverse action.

Many lenders have filters that will tell the applicant something like "that ZIP code is not in our market area and the application cannot be processed online. Please call or visit..."

Posting a notice will not stop the applications from being submitted, in my experience.