State Paid Disability - Absence Pay Reduction

Summary:

There are some instances where an employee receives disability pay from the state and is also eligible for Short Term Disability from our company. We need to reduce what is processed as Short Term Disability so that the employee is not overpaid. This amount is not consistent and we do not have a reliable way to receive the exact amount before payroll is processed.

Does anyone have suggestions on the best solution on how to reduce earnings of what the state paid? Another thing that we also require is taxable earnings must reflect that this reduced amount is not considered taxable earnings.