CP268 tells you we made changes to your return because we believe there is a miscalculation on your return. Overpayments occur when you get benefits and we later find that you were not eligible.You need to pay back these benefits to us. A paid tax return preparer who files Form 843 for you must sign the form and fill in the identifying information at the bottom of the form. Get free tax help from the IRS. File your taxes, get help preparing your return, help yourself with our online tools, find your local office – or call us. Telephone Information Center. Mon through Fri, 8 a.m. You get an overpayment credit when your tax payments exceed what you owe. You'll automatically receive a refund of the credit.