The only requirement imposed by NCEES to sit the FE is that you pay the exam fee. NCEES addresses this generally on their page about the FE:
Exam fees and requirements
An exam fee of $225 is payable directly to NCEES during the
registration process. Some licensing boards may require examinees to
file a separate application and pay an application fee as part of
their approval process in order to be qualified for seating for an
NCEES exam. Your licensing board may have additional requirements.
And again, more strongly-worded, on the third page of the NCEES Examinee Guide (emphasis mine):
Eligibility to sit for an NCEES exam varies by state/territory and is
determined by each licensing board. It is your responsibility to
review your licensing board requirements at ncees.org/boards
before registering for an exam.
So, how do you figure out the exact requirements in your state? Let's look at an example.
Massachussetts requires that an additional application form be submitted to and processed by their state board. This form is titled BOARD APPLICATION FOR THE FE AND/OR EIT CERTIFICATION and seems as though it can actually be used in the way you describe, by selecting the third option in response to question 21:
- Upon successful completion of the fundamentals exam, select the classification below that best describes your eligibility for
(c) Eligibility for EIT certification insufficient due to formal
education requirements or experience requirements; no certification
will be issued upon successful completion of the fundamentals exam.
This doesn't seem to strictly agree with the state regulations, though—specifically 250 CMR 3.01(7), which reads:
Once the Board has reviewed the applicant's education, Work
Experience, character and experience references, college transcripts
and documentation, the Board may schedule the engineering applicant
for an interview; and the Board shall schedule all land surveying
applicants for the mandatory oral exam. Once the Board has determined
that all applicable statutory requirements have been met, the
applicant will be scheduled to sit for the applicable written
This language assumes that the applicant is pursuing certification; it's not written to accommodate what you might call an "exam tourist" (if there is such a thing). But there's also 3.10(3):
Individuals who have passed the respective FE or FS Exam prior to
meeting the other certification requirements noted above must contact
the Board's administrator for the proper filing requirements for
Nearly all of the explicit requirements set out in that chapter are concerning the PE/PS exams rather than the Fundamentals exams; the only explicit requirement I notice concerning the Fundamentals is that you submit the state application. Practically speaking, it's possible the body that reviews that application has internal policies and procedures that would result in your application being denied, in which case you might have to appeal directly to the reviewing body.
Long story short, just read the applicable state regulations. If something is ambiguous or hard to understand, contact the state licensing board directly. Depending on your motivation for sitting the exam without an engineering background, however, they may not be inclined to help you and you might have to just try submitting the application and see if they let you in.
On the other end of the spectrum, California does not require any separate application, in which case you would just register with NCEES and pay the fee. If you live in such a state, you can create an account on the NCEES website and go through all the necessary steps to register for the exam during the open registration period. You will need to agree to certain terms, that you are who you say you are, etc., and pay the fee to NCEES. You will be prompted to provide information about your education and it's important that you answer truthfully. On the day of the exam, bring a printout of your registration and a photo ID.