To maintain your permanent residency
The most important aspect of maintaining permanent residency is to prove that you did not give up your intention of maintaining permanent residence in the United States. The intention can be proved by tax filings and driver license renewals. Permanent resident status does not seem to be much different from the citizenship status, but Permanent Residents are still foreigner under the US law and can be deported at any time. In particular, it will be important for you to maintain your permanent resident status for the first five years of your permanent residency.
1. Travels Abroad
If you are a US permanent resident traveling abroad for less than a year, and you want to re-enter the United States, you only need to have a Green Card and a national passport. However, if you have been abroad for more than one year, you must have a re-entry permit before you may enter the U.S. again. Therefore, if you need to stay in the US for more than one year, you must get a re-entry permit, and you should be in the U.S. at least until the time of receipt of the application of the USCIS, and at the time of fingerprinting. Re-entry permits are valid for two years at the time of initial issuance, a renewal after two years, and another one-year renewal, for a total of five years.
Even if you have been granted a re-entry permit and reside overseas, staying abroad for more than one year will discontinue “the continuous residence and physical presence of five (three) years in the United States from the date you acquired the green card”, which is required to obtain citizenship. As a result, to be eligible to apply for citizenship, you must remain in the United States for five (three) years from the moment you return to the United States to apply for citizenship.
If you are 14 years of age or older and reside in the United States for 30 days or longer and are not a US citizen, you must report the changed address within 10 days of moving, under section 265 of the Immigration Act. This is a compulsory regulation and may be considered a misdemeanor if you do not report an address change via the AR-11 form, and it may lead to detention or deportation. It is important to note that you must report each family member over the age of 14 even if a family member moves together, and make sure to keep a record in case of any incidents.
3. Expired/ Lost Green Card (I-551)
The concept of "green card (I-551)" is a proof of the status of permanent resident. Accordingly, your status of permanent resident does not disappear, even if a green card is expired or lost. There is no change in your legal status of residence in the United States. However, it is a legal responsibility of the permanent resident to have a valid green card. If it expires, renew it. If you lose it, you will have to reissue it. You also need a valid green card when you work, travel, and apply for benefits. Beginning September 20, 2018, the USCIS sends e-mail or text messages to green card holders who have expired or are about to expire.