There are many options available.
As mentioned by others, you could look at the options available in table view V_T51P6. The "Priority" column will help you to identify in which order to take the various deduction other than the mandatory ones (Taxes and other Statutory Deductions). Column Arrears will help you to identify what to do if a deduction can't be taken in it's entirety, and column Retroacct. will enable you to identify what will happen if it's a retroactive calculation.
Depending on your choices, table view V_T51P1 could need some configuration. For example, we have configured the Group Insurances so that the deduction is taken even if there is not enough earnings left to cover them and the system will automatically "loan" the employee enough money to cover that deduction (and recuperate the "loan" automatically as soon as possible), but we configured the Charitable Donations so that the portion that can't be deducted simply vanishes (goes into DDNTK but not ARRRS).
P.S.: As with any Payroll related enquiry, it would be preferable to mention for what Country Code.
