From Group finances, a tax can be set so that group members automatically contribute to the group fund when they complete a mission.
In Group -> Finances you will be able to "Set new tax rate". Current tax is shown in there. Default tax rate is 0%
Group leaders and a new permission called "Set group tax rate" allows the use of this function.
Maximum tax can be 0%-90%, two decimals.
When group members complete a mission and there is a group tax set they will see something like this:
"Congratulations! Mission successfully completed.
X.XX HPD transfered to your account.
X.XX HPD deposited to the group fund."
Have fun