A Request for Evidence (RFE) is issued by U.S. Citizenship and Immigration Services (USCIS) when they decide that they need more documents or information before they can make a decision on an immigration petition.
If one gets an RFE, there is no reason to think that the case will be denied and hence no need to hit the panic button. USCIS will usually give 30-90 days to allow for a RFE response. A timely response is extremely important. Otherwise USCIS can deem the immigration petition abandoned and can deny it. Reading the RFE several times and figuring out what exactly is requested is very very important. Then, the next step is to gather all the relevant information prior to submission. One only gets one chance to respond. One can completely and timely respond to the RFE. One can provide partial information but then USCIS can make a decision based on the partial information. One can also withdraw the application. It is important to submit all the information during the initial submission instead of trying to submit it piece meal. USCIS may not consider separate response submissiions after the initial submission. Of course, if a deadline is looming and one does not have all the information, it is better to submit something rather than nothing prior to the expiration of the deadline.
The response to this question is very fact specific. There are simple document requests for information and then there are complex requests. First thing to do is read, reread, and understand what is being requested. If it is a simple request for a document (such as a birth certificate) and one is comfortable in knowing that this is what the request pertains to, then it is up to the individual applicant to decide whether they warrant further assistance. If however, one is not sure or does not understand all the legal language or request, then it is time to at least consult with a qualified immigration attorney. Once one is informed on what is being requested, the timeline involved, the cost, and any challenges, then then he/she can decide whether counsel needs to be hired. The key here is to provide a complete and comprehensive response to the RFE. If that means hiring an attorney to do so is in the applicants interest, then this option SHOULD be considered.
Once a RFE is sent out USCIS stops working on the petition until they get a response. Once they have a response then they start working on the case and typically have 60 additional days to work on the matter. Sometimes it does take longer. If an applicant does not get any response within 94 days of the RFE response, then it is time to call the customer service hotline, make an info pass appointment, and or set up a consultation with a qualified immigration attorney.