If you wish to claim an exception to the English and Civics test that is a part of the naturalization process “because of physical or developmental disability or mental impairment” you have to file Form N-648, Medical Certification for Disability Exceptions with the USCIS. If you are capable enough to learn or demonstrate the required knowledge and understanding of basic English and Civics, you cannot apply for a waiver.
To claim a waiver to the tests, file Form N-648 along with your completed citizenship form, N-400. You will be eligible only if the medical condition(s) is long-term (lasting 12 months or longer) and the condition affects you so badly that you will not be able to take the English or civics tests. Once you submit the form, USCIS will review your form and finally determine whether you qualify for an exception to the citizenship test or not.
As far as filling the form is concerned, other than the “Applicant Attestation” section in the application, all other sections of has to be completed by a currently licensed medical doctor, doctor of osteopathy, or clinical psychologist (a medical professional). The doctor should have such professional expertise that he/she can diagnose and evaluate you for a physical or developmental disability or impairment that does not allow you to satisfy the English or Civics requirements. Apart from the doctor, an employee who is under the direct supervision of the certifying medical professional can also prepare the form with all the information verified by the medical professional. Even if the employee fills the form, it is the medical professional who signs the form who has to take responsibility for authenticity of the information provided in the form
It is important that the medical professional signing this form have adequate training and experience in the field of the disability that you have. The professional, generally has to be “the treating physician”. It simply means that he/she should be regularly treating you for the disability. If he/she is not your regular treating physician, you have to give adequate reasons for the substitution. A detailed information regarding the future plan of your treatment should also be included. Adding to these, he/she has to give an accurate assessment of your disability in understandable terms so that USCIS can easily understand and determine whether they can give you an exception from the English and civics requirements or not.
Under exceptional circumstances, it is not needed to file Form N-648 along with Form N-400. In such cases, you can submit the completed N-648 to the USCIS at the time of your interview. Though USCIS do accept delayed submissions, such claims may further delay the generally lengthy naturalization process.