User promotion based on Age

[CheeSie]

Well i need to somehow make my forum check the members age eachtime they update their profile, so if they're older than X years they get into a special usergroup, and if they under they get removed from that special usergroup..

I believe its quite simple, i've tried to make it my self but no luck

Its not a paid request, but i would very thankfull if you helped ..

ps. i've tried searching the forum, couldnt find anything that worked for me :/