Not necessarily. Section 349 of the U. S. Immigration and Nationality Act (INA), as amended, governs the right of a United States citizen to renounce his or her U.S. citizenship. It can only be done voluntarily and with the intention of relinquishing United States nationality. There is no such thing as an implied renunciation. Thus, it is not enough to simply re-acquire Philippine citizenship – you must do so with the intent of surrendering your U.S. citizenship.
This is the same for all other expatriating acts, such as taking an oath or making an affirmation or other formal declaration of allegiance to a foreign state or a political subdivision thereof; entering, or serving in, the armed forces of a foreign state if such armed forces are engaged in hostilities against the United States, or such persons serve as a commissioned or non-commissioned officer; accepting, serving in, or performing the duties of any office, post, or employment under the government of a foreign state or a political subdivision thereof – whether or not an oath, affirmation, or declaration of allegiance is required. In all of these cases, each must be performed voluntarily and with the intent to relinquish U.S. citizenship.
This intent can be established by affirming in writing to a U.S. consular officer that the act of expatriation was indeed performed voluntarily with an intent to relinquish U.S. citizenship. The consular officer will then proceed to prepare a certificate of loss of nationality and forward it to the State department for consideration and if appropriate, approval. Of course, a person always has the option under sub-paragraph (a)(5) of the afore cited INA Sec.349 to formally renounce U.S. citizenship before a diplomatic or consular officer of the United States in a foreign state, in such form as may be prescribed by the Secretary of State. This express renunciation is the clearest and most effective way to renounce U.S. citizenship.
In fact, the U.S. Department of State has adopted a uniform standard of presumption that citizens who obtain naturalization in a foreign state, or subscribe to a declaration of allegiance to a foreign state, or serve in the armed forces of a foreign state not engaged in hostilities with the United States, or accept non-policy level employment with a foreign government – intend to retain United States citizenship. And even in cases where there is no such presumption, the intent to relinquish U.S. citizenship must still be established. In your case therefore, the mere re-acquisition of Philippine citizenship – by and of itself – does not result in the automatic loss of your U.S. citizenship. If you affirm in writing to a U.S. consular officer that you reacquired Philippine citizenship voluntarily with the intent to relinquish U.S. citizenship, then you would lose U.S. citizenship. It you did not have such an intent, you should consider affirmatively asserting U.S. citizenship status with a contemporaneous written statement describing the reasons for the planned action and your desire to retain U.S. citizenship, submitted to the U.S. consul or the State department, to be included in their files. Continuing to pay U.S. income tax, keeping a U.S. passport, retaining property and other ties in the U. S. are all indicia that you did not intend to lose U.S. citizenship when you reacquired Philippine citizenship.