Legal disclaimer

My best disclaimer for this client would be "I am sorry but I am unable to help you at this time."

Try this:
We will prepare your income tax return(s) for the tax year 2007. Prior to preparation, it is your responsibility to inform us of your filing status, and all federal, state, county, municipal or other income taxing authorities to whom you are obligated. In addition, it is understood that you will provide us with all necessary supporting information for the complete and accurate preparation of your return(s). Any information you provide should have adequate documentation to support it in the event of a taxing authority audit. By signing this letter you declare that you have provided all pertinent tax preparation information which is supported by appropriate documentation. Your return(s) will be prepared without specific verification from information provided solely by you and will be processed in accordance with Statements on Standards for Tax Services as promulgated by the American Institute of Certified Public Accountants and appropriate federal, state, county, and municipal tax laws and regulations.