US Citizenship
All eligible green card holders can apply for US citizenship using Form N-400, Application for Naturalization. After completing the citizenship application, applicants have to mail it with the required supporting documents that are user specific and with the submission fee. The submission fee while applying for US citizenship is $595. Additionally $85 is charged towards biometrics (if applicable).

After you mail the application to the USCIS address that is mentioned in the instructions page that comes along with the application, the USCIS will send a confirmation for the application received. The notice will have a 13 digit number through which you will be able to monitor the progress of your case.Then you can expect a notification about the date you need to appear for fingerprinting. During this time, national security background checks are conducted and finally you will be informed to appear for an interview.

While attending the US citizenship test interview, you will be questioned on your application that you submitted and also about your background. Another requirement in the citizenship application process is that you need to pass the US citizenship test that will have questions related to the English language and Civics. It is normally required from every applicant that they can read, write and speak basic English and also that they have some knowledge about the US history and government. As far as the English section is concerned, reading, writing and speaking is tested.

Reading :
You should be able to read at least one out of the three given sentences correctly.

Writing :
You should be able to write correctly at least one out of the three given sentences and speaking, of course will be judged based on how you respond to questions.

Civics :
From a list of 100 available questions, ten questions will be asked and the officials expect you to answer at least six questions correctly. If you fail the test, you do get another chance and will be tested again within 90 days of having failed the first time.
Considering the age of applicants, the test is waived for certain applicants. Applicants who are above 50 years of age and who have been permanent residents for a total period of at least 20 years and also applicants above 55 years of age who have been permanent residents for a total period of at least 15 years need not take the English test. But they have to take the Civics test and can take it in a language per their preference.

Additionally, applicants above 65 years of age who have been permanent residents for a total period of at least 20 years need not take the English test. Even under this category, they have to take the Civics test and in a language of their choice but the test will be a simpler version. From a list of 25, 10 questions will be asked.

Applicants are eligible for an exception for the US citizenship test if they are having a medically determinable physical or mental impairment and if that impairment is affecting the ability to learn English and Civics. Such applicants should file Form N-648 to request an exception. Applicants claiming waiver of the English proficiency requirement should be prepared to bring an interpreter.