(a) Statewide guideline.--Child and spousal support shall be awarded pursuant to a Statewide guideline as established by general rule by the Supreme Court, so that persons similarly situated shall be treated similarly. The guideline shall be based upon the reasonable needs of the child or spouse seeking support and the ability of the obligor to provide support. In determining the reasonable needs of the child or spouse seeking support and the ability of the obligor to provide support, the guideline shall place primary emphasis on the net incomes and earning capacities of the parties, with allowable deviations for unusual needs, extraordinary expenses and other factors, such as the parties' assets, as warrant special attention. The guideline so developed shall be reviewed at least once every four years.
(b) Rebuttable presumption.--There shall be a rebuttable presumption, in any judicial or expedited process, that the amount of the award which would result from the application of such guideline is the correct amount of support to be awarded. A written finding or specific finding on the record that the application of the guideline would be unjust or inappropriate in a particular case shall be sufficient to rebut the presumption in that case, provided that the finding is based upon criteria established by the Supreme Court by general rule within one year of the effective date of this act.