There is a post from few years ago which is a common problem for us. We too are struggling with how to set up a disposable net rule which accounts for deductions which were in place when the levy order was entered vs. deductions which were voluntarily increased or employee signed up for after the tax levy was entered. According to our understanding of government regulations, any deductions in place at the time of the federal tax levy are to be included as part of the disposable net calculation. Any deductions which are voluntarily increased or for which employee signs up after the federal tax levy is already in place should be withheld from employee's net after the federal tax levy.
For example, we have someone whose net pay is $200 due to a federal tax levy. We have a company medical insurance change (involuntary) that will go into effect 5/1/14 that will not reduce his net pay (as it should not). However, if the employee makes a voluntary election to move from single to family coverage, then that SHOULD reduce his net pay and not the levy amount.
How could SAP distinguish between voluntary and involuntary deduction changes? Any suggestions on how to set this up in SAP? The way our current config rules are working is the employee is receiving the $200 net pay regardless of the circumstances surrounding deduction changes.