Repayments from employees?

What is the situation for all entrepreneurs who have employees in the field of psychotherapy have, if there are repayments the difference to the provisional tariff should occur? We put this question to a lawyer and received the following answer.

"The members have correctly recognized that they owe the wages, even if they are based on the "provisional" rate, which may be too high, and may therefore have to make a repayment. There are two approaches to the problem. They can be used cumulatively or alternatively. As mentioned by the member, provisions can and must be formed within the company. This must be discussed with the accounting department, but is not legally problematic. The risk of paying "excessive salaries" could be countered by no longer structuring the entire salary as a fixed salary. A fixed wage could be agreed that corresponds to the minimum according to a possible new pay scale, the worst-case scenario according to the pay scale, so to speak. The difference to the current salary could then be structured as a variable component, which is either paid out with a delay if the provisional pay scale is confirmed or which can be reclaimed if the company has to make a repayment. Of course, this requires an adjustment to the employment contract and can only be decided unilaterally at the next possible termination date."