Go to the employee profile > Pay > Withhold given wage advance.

Select the starting period that you want to withhold the advance from. Most of the times the next period the employee gets salary for. When you select one in the past, where the employee already has gotten salary, nothing will happen.

Add the amount you want to withhold.

When the amount to withhold is higher than the net amount the employee gets paid on their next payslip, the remaining amount will be taken from their next payslip(s).

So if you want to withhold €2000 and the next payslip is €1500 net salary, the remaining €500 will be taken from the payslip after the upcoming payslip. The upcoming payslip will be €0 for the employee. As all of their money will go to the withholding.

If you want to prevent this, you can add a separate withholding for each month. For example you add a €500 withholding in this month, €500 in the next, etc.

You are not able to automate this and decide how much to withhold each month. You will have to add this withholding manually every month.

In order to see the withholding on the payslip of the employee, you need to finalise their payslip first. You do this by adding the payslip to a payment batch and creating the batch. You could always do this and remove the batch again if you want to be certain you've added it correctly.