In general, government mail sent by the USCIS to your old address will not be forwarded to your new address. Instead it is sent back to the USCIS marked "undeliverable". This can cause you a lot of problems.
To be safe, we highly recommend letting the USCIS know that you have moved in three separate ways:
1. Send Form AR-11 to the USCIS via certified mail (keeping a copy of the form);
2. Submit your address change to the USCIS online (directions below), which also utilizes Form AR-11; AND,
3. Submit your address change to the USCIS online for certain forms that you submitted as part of your AOS package.
To change your address via certified mail, complete and mail Form AR-11. Download this form and print it out by accessing the USCIS website at www.uscis.gov. First, click on "Forms" found at the top left hand side of the website, and then click on "Form AR-11 Change of Address." It is a very simple one page form to fill out. As mentioned, be sure to keep a copy of Form AR-11 before mailing it, and mail it via certified return receipt mail so you not only have proof that you mailed Form AR-11, but will also have proof that the USCIS received it.
The mailing address to send Form AR-11 to the USCIS is:
U.S. Citizenship and Immigration Services (USCIS)
Change of Address
1084-I South Laurel Road
London, KY 40744
The reason we also recommend notifying the USCIS that you have moved using the online system (which is fairly new) is that, from experience, after Form AR-11s are mailed to the London, Kentucky office, nothing appears to be done with them.
Change your address online by accessing the USCIS website at www.uscis.gov. Click on "Online Change of Address" currently on the left hand side of the page under "After I File". The system will direct you to Form AR-11, which you can fill out and submit online. After you submit Form AR-11 online, print both a copy of Form AR-11 and a confirmation page proving that you submitted it to the USCIS. Unfortunately, like submitting a hard copy of Form AR-11 through the mail, the USCIS may or may not do anything with the generic online change of address information. Therefore be sure to proceed to Step 3.
Immediately after you change your address online according to Step 2 and you submit Form AR-11 online, the system will ask if you would like to enter the receipt numbers for specific applications that you already filed with your AOS package. Enter the receipt numbers for the three most important applications that you filed with your AOS package: These are the I-485, I-131 and I-765 applications. The system will allow you to print out a confirmation for each receipt number for which you submitted a change of address.
OTHER PROBLEM SOLVING STRATEGIES
It appears that 90% of the time, these change of address techniques are effective. However, sometimes government mail sent from the USCIS is still sent to your old address, even after you have taken the precaution of filing your change of address using all three methods described above.
Two other solutions to update an address change with the USCIS are to schedule an INFOPASS appointment with your local USCIS office and/or ask a local Congress staff member to submit a congressional inquiry to confirm the change of address.