Identify the snake beyond argument
Start the document with the animal himself: species and full morph description, sex and how it was confirmed, age, current weight, and the date of his last feeds and shed. Add clear photographs from above and the side showing his pattern. Corn snakes of common morphs look very alike in someone else's rack, and a season later, memories differ. If he is microchipped, write the number down. This identification block protects both keepers — the borrower can prove which snake is yours, and you can prove the snake that comes back is the one that left.
Dates, duties, and costs while he is away
State when the loan starts, when he is expected back, and what ends it early. Write down who feeds him and on what — most loans expect the borrower to cover food and running costs — and, more importantly, who pays if he needs a vet. Agree what the borrower should do if he refuses food for an extended stretch, escapes, or falls ill: who gets called first, and whether treatment can go ahead before you are reached. Breeding males commonly go off food during the season, so note his condition at handover; that shared starting point prevents a thin returning snake from becoming a dispute about whose care failed.
Quarantine and health, both directions
Record his health status honestly: any past illness, treatment, or mite exposure in your collection, and ask the same of the borrower in writing. Agree the quarantine he will get on arrival at the borrower's — housed separately, handled last, watched for a settling period — and mirror it when he comes home, because he will return having shared air and possibly equipment with another collection. This section feels formal between friends and is exactly where experienced keepers are most careful; disease passed on a breeding loan can cost both collections dearly.
The offspring agreement
Settle the eggs before there are any. Note which female or females he will be paired with, who owns the eggs, who incubates them, and how hatchlings are divided or sold — a straight split, first pick alternating, or a fee instead. Include what happens if the pairing fails or the female becomes egg-bound, since her care costs arise from the project you both entered. Writing this down while everyone is friendly is easy; reconstructing it over a clutch of hatchlings is not.
Cover the journey itself in the document as well. Note how he will be transported — a secure tub with ventilation, kept dark and at a safe temperature — who is responsible for him in transit, and the latest time by which he should be settled at the other end. Agree that the borrower confirms his safe arrival the same day. Loans rarely go wrong on paperwork details, but when a journey is delayed or a tub is dropped, a written plan is what both keepers fall back on.
Send a copy of his records with him and keep the signed loan note with his file in KinsLe's Pet Passport, so his identity, condition, and care history travel as one packet and return with him.