Ditto what Amanda said. They should pay for everything. His transportation, coggins, health cert, feed, wormer, (you should do all shots before he leaves to help protect him), medical care, and insurance on him - making sure you are the beneficiary.
Things to think about... If you offer LFG, does that mean your stallion has to travel back next year and the year after, etc? Specically spell out the medical care because not everyone thinks the same way when it comes to "complete" care. What will they feed him? Will he be kept (housed) in a manner you are comfortable with? How often should his feet be done? How do you guarantee their farrier knows what he/she is doing and won't ruin your horse's feet? What if a mare kicks him and he becomes sterile? Is the insurance money worth no longer having a producing stallion? What if he brings an STD back to your farm? Will you require all their mares be pre-tested? What if something happens at that farm that impacts him psychologically and when he returns, he's not the same breeder he was before? What if their mares are not good producers? Do you want your stallion bred to inferior mares? Will you get to select which mares he's bred to? Will you let them stand him to mares they don't own? If so, how gets that money?
So much to think about. I speak from personal experience... It's not worth it. You can do all your homework, think he will be fine, believe it's ok because you're sending him to a "friend." In the end, you may no longer be friends.
Ask yourself why you should do it? What will you get from it? Do you need a break from having a stallion for a year? Do you need the money? Do they have exceptional mares so maybe it will be a good thing for your boy? Aside from those few things, I can't imagine what it does for you.
Best of luck to you in your decision.
