A person can retake the Series 63, 65 or 66 exam an unlimited number of times, so long as applicable waiting period requirements have been met, according to the North American Securities Administrators Association (NASAA).

After a person fails an exam the first time, there is a waiting period of at least 30 days before the second taking of that exam can be scheduled. After a second failed attempt, there is another waiting period of at least 30 days. If an exam is failed three times or more, there is a waiting period of least 180 days for scheduling each subsequent retaking of the test.

Waivers of the 180-day waiting period are granted only rarely. As stated on NASAA's website, the reason for this is that the test questions are selected at random from an existing question bank, and if a test is taken enough times, the same questions recur. The exam then becomes a test of memorization rather than competency.

The waiting periods, however, are exclusive to each of the NASAA exams. This means that if a person fails the Series 63 exam, formally known as the Unified Securities State Law Examination, there is no waiting period for taking either the Series 65 test (NASAA Investment Law Examination) or the Series 66 test (NASAA Uniform Combined State Law Examination).

Most states, but not all, require a person to pass the Series 63 exam to become a licensed securities agent. However, requirements to become an agent vary by state.

The waiting periods for the Series 63, 65 and 66 exams mirror those in place for exams sponsored directly by the Financial Industry Regulatory Authority (FINRA) for the career advancement of financial professionals..

FINRA administers the Series 63, 65 and 66 exams on behalf of NASAA.

FINRA is a regulatory body created after the National Association of Securities Dealers merged with the regulation committee of the New York Stock Exchange. FINRA is vested with responsibility for governing business between brokers, dealers and investors.