No.

But FWIW, you could rank them up the year they turn 16 if you really needed to.

Otherwise, I'd say just keep ranking them in the kids ranking. They'll never be ranked in that system ever again, so just let them chill and experience it.

Skill wise they are a blue belt, but maybe not the other aspects they should develop at that level. In my opinion behavior and mental growth should be a factor. In the case you mention the 14 year old actually could be there not only with the physical skills but with the level of maturity they need. You are the instructor and have the ultimate choice on this. IBJJF regulations matter in that competition. On popular competition for children would be NAGA. At 14 they would have to compete with the teen expert division regardless if they were a blue or green belt.

I do however agree with Robert, that you should let them enjoy where they are and get that experience.
Bottom line it is up to you as his professor and to do what is best for that individual.

I am interested to see what others think as well.

I do not promote anybody from our kids classes to bluebelt.
The highest rank is a green belt for kids at our gym.
Turning 16 a promotion is instantly possible, if the student has the skills.

We have had 2 examples during the last years who were 14 and 15 years old and had bluebelt skills.
In both cases they had to wait and that was o.k. for them because of the quite clear guideline:
blue-purple-brown and black are adults ranks.

No

I only teach adults, so I haven’t run into this problem myself, but I would be hesitant to promote a kid under 16 to an adult rank because…

(1) I’m not sure where they would place that kid in competition. Because of their age, they would be in the kids’ division, but under which rank? Would they compete as a green belt? A tournament might decide that they can’t compete (e.g., an IBJJF tournament).

(2) I would rather that a kid be the best green belt in the room than the worst blue belt. It’s honorable to be a green belt who can hold their own with adult blues, but it’s demoralizing for a kid to get crushed by their fellow blue belts (who then might go on to whisper in the locker room about how the kid got promoted too early). Being a green belt in the kids’ class means that you’re at the top of the pecking order. Let the kid enjoy that for a while before they have to move on to the adult class and get smashed by the purples and browns. :)

(3) We don’t want BJJ to end up like the McDojo styles that give adult ranks to kids. I like the fact that BJJ has a totally different color system for kids and you can’t earn blue/purple until 16 years of age, brown until 18, and black until 19.

Technically they only need to be turning 16 that year. So virtually everyone is 15 when they are eligible.

The elite level kids, green belts with 10 years exp will at times be promoted at the end of the year, slightly early. In advance of their juvenile blue year. That's fine imo.

But to be really honest, if this 14 year old only has 2 years exp. They are no where near green belt or blue belt.

The solution there is easy. They can't compete. Same as any body promoted to a rank that is ahead of comp age range schedule (17 year only brow belt, 18 year old black bet etc).

Thanks for everyone’s opinion. I have gotten enough to make a informed decision on it. No one in my gym competes so completion rules and ranks are not a big issue. But I appreciate everyone’s input. None-the-less.