Applying for U.S. citizenship for a Filipino fiancee is a long process. It starts with the application for immigration to the U.S. through the acquisition of a green card. After being married and living with your wife for the past three years - and fulfilling the continuous residence requirements of not leaving the U.S. for longer than six months, you can apply for naturalization to make your wife a U.S. citizen.
Apply for a K-1 visa at the U.S. Embassy in Manila and attend the visa interview with all the requirements. Bring all important documents including photo identification and other legal and personal documents establishing the relationship with your fiancee. Prior to the interview, your fiancee also needs to fulfill the medical and vaccination requirements as stated on the website of the U.S. Embassy in Manila. A packet containing the long list of documentary requirements will also be sent.
The processing usually takes about six to seven months. You will be updated about the status of the visa petition through a series of correspondences. This will be mailed and emailed to your registered mailing and email addresses and each letter will be labeled as "notice of action" (NOA).
Wait for the approved K-1 immigrant visa to be placed in her Philippine passport, then enter the U.S. within 90 days from the date of entry stated in the visa. You may get married in the Philippines or in the U.S.
Wait for your fiancee to receive her green card, which usually takes about a month. The green card will be mailed in the registered address stated in her visa application.
Apply for naturalization using form application for naturalization form at your local U.S. Citizenship and Immigration Services (USCIS) office. Prior to the application, your wife must fulfill all requirements.
An applicant must be at least 18 years old and currently married to and living with a U.S. citizen for the past three years. Your wife must also fulfill a permanent resident's continuous residence requirement. This means that if she leaves the U.S., she can't be gone for six months or longer in order to complete her three-year residence in the country. Otherwise, she will start all over again for the required continuous residence requirement before she can apply for naturalization.
Complete all personal and legal documentary requirements determining you and your wife's identity and relationship. Apart from the application form, you must also provide two passport-style photographs of your wife. The long and updated list of documentary requirements can be found in the USCIS handbook "A Guide to Naturalization."
Send the application with the fee for processing a naturalization application to the appropriate lockbox facility or service center in your state. As of June 2011, the total fees amount to $680, but the amount may change without prior notice. You may pay using a check or money drawn on a U.S. bank. This should be payable to the "Department of Homeland Security."
Wait for the USCIS to schedule an appointment for her fingerprinting and interview. In some cases, the application may require mailing additional documents for the application as well.
Attend the interview scheduled by the USCIS. If she can't make it to the scheduled interview, you may request for rescheduling by writing to the office where the interview will be conducted. However, rescheduling may add several months to the process, which can already take about six months from the filing of the application. Failure to attend the interview without notifying the USCIS will result to administratively closing of the application. The application will be denied if you don't contact the office for new interview schedule within one year after the closing of the case.
Attend the oath of allegiance to the U.S. through a formal naturalization ceremony. There are some states that allow taking the oath on the same day as the interview. The USCIS will provide a notification of the ceremony date using the notice of naturalization oath ceremony. You may request for the rescheduling of the oath by writing to the USCIS. Include a copy of the notice of your prior schedule to your letter, then wait for a new notice telling you when the new date for your oath ceremony.