CP268 tells you we made changes to your return because we believe there is a miscalculation on your return. You get an overpayment credit when your tax payments exceed what you owe.You'll automatically receive a refund of the credit. This notice tells you that all or part of the overpayment on a return you filed was applied to other federal taxes you owe. You can find the CP or LTR number on the right corner of the letter. You received this notice because the deposits or payments applied to your account didn't agree with what you claimed on your federal tax return. What this notice is about. You have a remaining balance due on a tax period after an overpayment (offset-in) was applied to your account. The IRS states that it takes 46 weeks to receive your refund of overpayment. Yes, there is a form to file.