Since you are the one writing up the contract, you can put in just about anything you want, including terms under which your % would increase and to what extent. Since it sounds like you will be an Independent Contractor, be certain the contract spells out that you will be an IC and what will be provided for you vs what you will provide yourself. In general, being an IC means you work for yourself, just in the room you are renting from him. That means you will need to do your own marketing, scheduling, billing, record-keeping, etc. He doesn't get to do those things for you when you're an IC... unless the contract gives him that power.
My recommendation is that you should continue to work at the chiropractic office for a bit longer while you do the necessary research to understand how to write up the contract. Once you have a rough draft done, have some more experienced MTs take a look and get their input on what you missed. Put that stuff in (if you want to), then have a lawyer take a look at it and help you finish it. While it may cost you a little bit for that legal help, it could pay off big time later on.
If the other MT is unwilling to sign the agreement you write up, make him state his objections in writing so you two can work out solutions to the points of disagreement. Once a verbal agreement is reached, amend the contract accordingly and get his signature. Once you and he have both signed the agreement, you can start working there. Hold him to the agreement and expect him to do the same with you. While it may take a bit of getting used to, you will be very, very happy you have a signed contract if anything questionable arises.
Jason Erickson, NCTMB, ACE-CPT, AIS-TA
Massage Therapist, Personal Trainerhttp://www.CSTMinnesota.com
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