The comment I have to make on this is that while this is an option the N-600 can take a long time to process whereas recognizition of citizenship by the same procedure is a lot faster by applying for a US Passport. We looked into both routes, and in Seattle Erin got her passport within 6 days with expedited processing (even though we were "Reclaiming citizenship" and had very unconventional paperwork) whereas current processing times for an N-600 at that time were over 12 months. The State Department seems to run a lot smoother than USCIS typically. And of course the US passport has been perfectly sufficient for everything as proof of citizenship for Erin from federal grant applications to travel to employment. So I strongly suggest going this route instead of the N-600 (which is more expensive to boot). However refer to the USCIS instructions as well on acceptable documentation for your claim etc.
With regard to taxes, we dealt with this too. There is a "saver clause" which basically says that if you file for your back taxes (typically past 3-6 years. See the US consulate in Frankfurt's website for IRS information on this) which says that even though you are legally penalizable for not filing taxes (since you were "always" a US citizen if your claim was valid) if you file before they catch you, then you wont be held liable. If ont he other hand, they catch you before you file, then I have heard of cases of heavy penanties. Again consult an attorney.
Muraari
QUOTE (lucyrich @ Dec 11 2007, 01:56 PM)

The answer is probably in INA 301 (go to the
USCIS website, click on "laws and regulations", and click on "Immigration and Nationality Act", and look for "ACT 301". That describes people who were citizens at birth. It may be that you need to find out what the law was at the time you were born.
If you qualify, you can file an
N-600 with the USCIS. Describe the details of your situation. If they agree that you qualify, you'll be given a certificate of citizenship.
You can apply for the certificate as an adult. But as time passes, it may be harder to show the evidence of your father's citizenship and residence.
Also, be aware that this would NOT be applying for new citizenship, but would instead be recognizing your US citizenship that you have held since birth. You may want to consult with an attorney before you do this. US citizens are required to pay taxes on worldwide income, and male US Citizens are required to register for selective service (military draft). That's true regardless of where the US citizens live, and regardless of what other citizenships or nationalities they may have. Assuming you haven't registered for the draft or filed US taxes, you've probably been in violation of these laws if you were a US citizen. I'm not sure what the consequences would be if you now apply to have your US citizenship recognized.