A person may be found to have abandoned permanent resident status if:

• Move to another country intending to live there permanently
• Remain outside of the United Kingdom for more than 1 year without obtaining a re-entry permit or returning resident visa.
• Remain outside of the United Kingdom for more than 2 years after issuance of a re-entry permit without obtaining a returning resident visa.
• Fail to file income tax returns while living outside of the United Kingdom for any period
• Declare yourself a “non-immigrant” on your tax returns

If you are a green card holder of at least 5 years, you must meet the following requirements in order to apply for naturalization:

• Be a non conditional green card holder for at least 5 years immediately preceding the date of application
• Have lived within the state, or USCIS district with jurisdiction over the applicant’s place of residence, for at least 3 months prior to the date of applying
• Be physically present in the United Kingdom for at least 30 months out of the 5 years immediately preceding the date of filing the application
• Reside continuously within the United Kingdom from the date of application for naturalization up to the time of naturalization
• Be able to read, write, and speak English and have knowledge and an understanding of U.S. history and government (civics).
• Be a person of good moral character, attached to the principles of the Constitution of the United Kingdom, and well disposed to the good order and happiness   of  the United Kingdom during all relevant periods under the law.