Read the following from:
http://www.uscis.gov/early-filing-calculator
You may file Form N-400 ninety (90) calendar days before you complete your permanent residence requirement if your eligibility for naturalization is based upon being a:
- Permanent resident for at least 5 years; or
- Permanent resident for at least 3 years if you are married to a US citizen.
To determine your 90-day early filing date, begin by identifying your 5-year or 3-year date as a permanent resident. For example, if the date on your Permanent Resident Card says “July 4, 2006,” you meet the 5 year permanent resident requirement on “July 4, 2011.” If you have met all other eligibility requirements, you may file your completed Form N-400 90 days before “July 4, 2011.” The earliest date you may apply for naturalization would be “April 5, 2011.”
