NEW YORK ( TheStreet) -- Here are some mistakes to avoid when looking for a tax preparer: Do not choose a person who isn't registered with the Internal Revenue Service. Make sure the preparer has a Preparer Tax Identification Number. Only those individuals who have registered with the IRS and received a PTIN are permitted to prepare returns for compensation. Do not choose a preparer who guarantees you a bigger refund, or who guarantees a refund, period. No tax preparer can guarantee you a refund if your individual facts and circumstances do not warrant a refund, unless he makes up deductions or exemptions or purposely does not report all your income. The only claim or guarantee any legitimate tax preparers can make is that by using their services you will pay the absolute least amount of federal and state income taxes possible. Do not choose a preparer who charges a percentage of your refund. Chances are the person will inflate your refund improperly to increase the fee. The fee for preparing a tax return should be based solely on the amount of time involved and/or the number of forms and schedules required. Do not choose a preparer who advertises you can walk out of the office with a check in your hand. That person or firm is not selling competent and accurate tax preparation -- they are selling usurious Refund Anticipation Loans. You want to use a tax preparer that is experienced and knowledgeable in tax law and not a loan shark. Do not choose a preparer who won't sign your finished returns. All tax preparers are required by the IRS to sign all tax returns that they are paid to prepare.