Hello, I applied for Naturalization earlier this year and a USCIS Representative notified me over the phone and by e-mail that I may already be a U.S. Citizen based on the Child Act of 2000; my citizenship is derived from my father who is a naturalized U.S. citizen and I meet all requirements under the act. I was advised to apply for a N600 or an application for a U.S. Passport in order to determine my actual status. Applying for my first U.S. Passport requires evidence of citizenship and I do not have any. So, is it in my best interest to send a N600 application? I'm a little disappointed that the $685 N400 filing fee is non-refundable but I knew that from the beginning. Applying for N600 will cost me another $600. Can I file for my first US Passport without any proof of citizenship? My father has his Certificate of Naturalization and I wonder if that will suffice? Any input is greatly appreciated!