Once you have determined that USCIS or a consulate is taking longer than it should to act on your petition or application -- as described under "When Should You Start Asking About Delays in Getting Your Green Card Approval" -- the question becomes, what you can do about it? Your best course of action depends on where your application is.
Delays at a USCIS Office
If any office of U.S. Citizenship and Immigration Services (USCIS) has your application, and it has been there beyond the normal processing time, probably the most effective way to make an inquiry is to speak face-to-face with a USCIS Information Officer.
For most USCIS offices, you need to have an appointment to speak with someone, although in a few, they will talk to you even if you drop in. To make an INFOPASS appointment, go to infopass.uscis.gov. Follow the instructions. You will need a current photo identification to get into the office. Of course, only people who carry proof that they are in valid immigration status should do this. The appointment is free.
It is possible that the INFOPASS information officer will be able to resolve your case problem while you wait. More likely, however, the officer will take information from you and begin the inquiry process, then let you know when to expect a response.
Another way to make an inquiry, which does not involve traveling to a USCIS office, is to call the USCIS Customer Service number at 800-375-5283. Although the person you speak with will most likely not be able to tell you anything useful during that call, he or she will start an inquiry and tell you when to expect a response.
The least useful course of action is to write a letter to USCIS. You are unlikely to get a response, except perhaps a boilerplate letter suggesting that you either call the Customer Service number or make an INFOPASS appointment. The one exception is if you were already interviewed and were told that you should expect to receive a decision by mail. In this situation, if you do not want to make an inquiry through INFOPASS or use the Customer Service number, you can write directly to the office where you were interviewed and ask for a decision on your case.
Although you may feel frustrated by delays in your case, remember to be polite. The officer you are speaking with is not the one who caused your delay; in fact, this officer is the one you are relying on to help you. You may be justifiably outraged by USCIS’s action or inaction, but never insult or threaten the officer with whom you are speaking. At best, such behavior is never helpful; at worst, it could be interpreted as a threat, which could lead to criminal prosecution as well as a quick denial.
Delays at a U.S. Consulate
If the NVC delays in sending your case to the U.S. consulate in your home country, you can email a case-specific inquiry to firstname.lastname@example.org, or call 603-334-0700. Be ready with your NVC case number, which you’ll find on all correspondence from the NVC.
If your case is delayed at the consulate after the interview, you will need to find out how that particular consulate prefers to receive inquiries. The possibilities are: visiting, calling, or writing a letter. Be sure to provide your NVC case number.