Best Option: Attach fee schedule and require your consent to changes.
The best way to plug this loophole in your plan contracts is to attach the fee schedule to the contract, make it clear that the schedule is incorporated into the contract, and bar the plan from changing it during the contract without your consent. Many plans will agree to make this change if you raise the issue. Plans are most likely to agree if you have some negotiating leverage or if the plan needs your services. For instance, a plan may want to add you to its panel so that it can expand into your geographic area or so that your specialty will be represented on the panel.
Here is a sample contract language you can use:
Plan shall pay Provider for Covered Services rendered to Plan Members in accordance with Plan's fee schedule dated [insert date] attached hereto as Exhibit [insert #] and incorporated by reference herein. Changes to Exhibit [insert #] shall be made only upon mutual written consent of Plan and Provider.
If your contract has an automatic cost of living or other escalator clause, be sure to exempt that from the mutual consent. It would unnecessarily delay the increase's implementation. To exempt that type of clause, add a phrase to the last sentence of the model language above, such as "except for the annual cost of living increase, as provided in Exhibit [insert #]