Promoting

Basically got my brown belt over a year ago, don't coach officially although have been offered, train 2 white belts friends in their garage on the side once or twice a week for fun, one trained at an Academy till his 3rd stripe on white and in my opinion is now at blue belt level and has been for a long time, is it acceptable for me to give him a blue belt? What are the unwritten rules around this? Would my gym see it as a problem? Should I tell them I'm thinking of doing it? Anything else to consider? The guy deserves it but has a young family and big mortgage and is not going back to paying at an official Academy or gym any time soon.