RC vs. NW certification

I think the advantage of the NW certification is that you do not actually need reasonable cause. The guidance seems to recognise that because it includes negligence in its definition of nonwillfulness. "Non-willful conduct is conduct that is due to negligence, inadvertence, or mistake or conduct that is the result of a good faith misunderstanding of the requirements of the law."
 Of course, a taxpayer with this profile joining the streamlined program will likely not be questioned by the IRS (provided it is laid out summarily in the certification), so the advantage of the streamlined program is that it gets resolved with minimum hassle (albeit with no Form 906).   The opt out will likely require a taxpayer interview and a return preparer interview (with document request for the organizer or other documents). So, the streamlined might be the path of least engagement in most cases. That might be worth just paying 5% and moving on.For an RC Argument, it is just that. It's used in a context of a penalty assessed by the IRS, in litigation, or Opt Out of an OVDP. It's usually longer, more detailed, lays out all the facts, ties in IRS statutes & cases, and pretty much explicitly spells out the nonwillful nature of one's fact & action pattern regarding the noncompliance. A RC letter asserts BOTH reasonable cause & good faith conduct.
The NW certification is already giving you a "line", so to speak. It has pretty much spelled out that your actions were, for the most part, nonwillful. The last page has a blank space for you to fill in more detail, but I imagine, most taxpayers woud want to be as brief as possible and echo some of the same verbage listed in the NW certification itself. (i.e., that many taxpayers were unaware of their global income or asset reporting rules for IRS tax filings, the knowledge of an FBAR, etc.). This section is not looking for, necessarily, a bullseye reasonable cause. The recommendation to TRANSITION into the streamlined program (SDOP) would be made by the OVDP examiner & manager to a committee of IRS managers. If there were some pieces of information shared by a bank, a foreign financial insitution, or other gleanings from the OVDP examiner on one's OVDP case, then an OVDP participant's transition to SDOP would probably be denied. In that scenario, it would not matter what one would have written on the NW certification, within reason, because the "application" to transition, if you will, would have been denied, and the only consequence is of course, to be back in OVDP.  The showing of full RC on NW is not necessary because the determination, from my understanding, would be made on a compendium of evidence, and not just what one writes on the narrative portion of the NW certification.

But what is exactly negligence, or inadvertent mistakes is not always easily discernible. That's the variable here.
The absence of any willful intent, willful blindness or conscious avoidance is what you want to look for in your case. The latter two are more of a challenge for the govt to prove so even in an instance where a taxpayer would have very little to prove his non willfulness, the absence or dearth of evidence for willful blindness & conscious avoidance would be a determining factor to label a taxpayer non willful. It's, "a state of mind. It is usually established by drawing a reasonable inference from the available facts.

 FBAR Willfulness Penalty - Evidence
http://www.irs.gov/irm/part4/i...
http://federaltaxcrimes.blogspot.ch/2014/07/interesting-article-from-swiss-bankers.html