Notice of Action (NOA), Form I-797, is a letter mailed by USCIS to an immigrant petitioner to communicate the latest update and next steps for their petition. It's a form with information from USCIS, not a form that applicants fill out. There are important details listed on the letter that pertain to the applicant's case, so applicants are advised to keep this letter safe as it might represent certain immigrant status before the case is completely approved. There are several different types of notice of actions.
I-797, Notice of Action
Also as known as an approval notice. USCIS issues this once they reviewed the case and then determine its approval. It normally will be the second notice of action letter from USCIS (NOA2) when there's no RFE requested. Depending on the petition type, it either means you will receive your green card soon, or USCIS has forwarded your case to the next agency to move your application or petition forward.
I-797A, Notice of Action
USCIS issues an I-797A as a replacement Form I-94 when an application of status change has been approved. It's only issued to people who are currently in the United States. It means the applicant can continue their stay in the U.S. through the new date listed on the Form I-94.
I-797B, Notice of Action
USCIS issues Form I-797B when they approve an alien worker petition. It's issued to both people who are currently in the United States and to aliens who apply in their home countries. Unlike form I-797A, a form I-94 won't be attached in an I-797B. Aliens residing outside of the U.S. must go for visa stamping in their home country before entering the U.S.
I-797C, Notice of Action
USCIS issues Form I-797C for numerous reasons which include:
USCIS issues a receipt notice when a petition and payment for filling fee has been received. It's the first notice of action letter (NOA1) from USCIS after filling the petition. Receipt notices contain the receipt number used to track the case. You must check all the information listed on the letter and if any information is incorrect, you need to contact the USCIS as soon as possible at 1 (800) 375-5283.
USCIS issues a rejection notice when a petition and payment for filling fee has been rejected. It might be because the filling office is wrong, filing forms or support documents are incomplete or the fee is incorrect.
USCIS issues a transfer notice when a petition or application has been transferred to a new USCIS office. To balance the processing times and workloads, USCIS will transfer some cases to other office according to the workload.
Re-Open Case Notice
USCIS issues a re-open case notice when a case has been reopened. This is when a case was initially denied but has been reopened for another review.
I-797D is the notice letter which accompanies certain benefit cards after USCIS approves an application or petition. The benefit card can be a permanent resident card, EAD card (employment authorization document) or I-765 combo card(EAD/AP).
I-797E, Notice of Action
Form I-797E is more commonly known is a request for evidence (RFE). It's the notice issued to request more information or documents to support a submitted application or petition. In the letter, USCIS will state the allowed time to submit the requested documents. Failure to respond in the requested time will delay and may result in a denial.
I-797F, Transportation Letter
USCIS issues a Form I-797F after a From I-131A, Application for Travel Document has been approved. It's the application for U.S. permanent resident who has been outside the U.S. for less than one year whose green card has been lost, stolen or destroyed to return to United States. It's also issued to a green card holder who has stayed outside the U.S. for less than two years and his or her reentry permit has been lost, stolen or destroyed.