You do not need to be sponsored by a member firm in order to write the Series 66 exam. However, it is important to remember that successful completion of the Series 7 is required in order for an individual to become fully-qualified, and this exam must be completed within a reasonable time period. Since the Series 7 exam requires sponsorship, it will be difficult for a candidate to obtain their Series 66 without a sponsor.
Alternately, if the Series 7 exam was successfully passed previously while sponsored, and this exam has not expired (by failing to register as a Registered Representative within 2 years of passing the exam, or having terminated registration at a member firm more than 2 years ago), you may still be eligible to write the Series 66 exam and register as an Investment Adviser Representative. Click here
to check with your local State Regulator on their policies.