Hi- Welcome to Just Answer and thanks for your question.
The current fee for filing a N-400 form (Application for Naturalization) is $680.00. People may be granted a fee waiver based on an inability to pay. I f you need this service, please consult http://www.uscis.gov/feewaiver
The following webpage will give you links to forms, fees, requirements, etc.:
For further questions, you can contact the National Customer Service Center toll-free at
Good luck to you in your endeavor! Please click the ACCEPT button so that I can receive credit for my work. Positive feedback and bonuses are always greatly appreciated.
Please let me know if you need anything further, then click the ACCEPT button so that I can receive credit for my work. Thanks!