Am I old enough to qualify for the course?
Each state legislature picked its own age threshold when it passed the mature driver law. Fifty-five is the most common starting point — used in California, Florida, New York, Texas, Pennsylvania, Illinois, and many others. A few states (such as some versions of the AARP-administered program) use 50 as the qualifying age, and a handful use 60. Some states also require state residency at the time of completion for the insurance discount to apply, which matters for snowbirds and recent retirees who may be insured in one state and registered in another.
If you're close to a threshold birthday, check the DMV's mature driver page for the exact minimum age and any residency requirements before enrolling. Completing the course a few months before you cross the age line means the certificate is valid but the discount may not activate until your next policy renewal after the age threshold. The course content and certificate themselves don't expire based on age — only the discount window does — so the worst case of an early completion is that the savings start later than the certificate.
For couples where one spouse qualifies and the other doesn't yet, the qualifying spouse can complete the course immediately and the second spouse waits until the age threshold. The household discount applies to the qualifying driver's portion of the policy, with the additional discount activating when the second spouse completes their own course. There's no benefit to coordinated timing if one spouse is below the threshold — earlier is better for the qualifying spouse, and the non-qualifying spouse waits until their age allows it.