68 Pa. C.S. § 5313
Any amounts accumulated from assessments for limited common expenses and income from the operation of limited common elements to which those limited common expenses pertain in excess of the amount required for actual limited common expenses and reserves for future limited common expenses shall be credited to each unit assessed for a share of those limited common expenses in proportion to the share of those limited common expenses so assessed. These credits shall be applied, unless the declaration provides otherwise, to the next monthly assessments of limited common expenses against that unit under the current fiscal year's budget and thereafter until exhausted. Any amounts accumulated from assessments for general common expenses and income from the operation of the common elements, other than limited common elements with regard to which limited common expenses are assessed, in excess of the amount required for actual general common expenses and reserves for future general common expenses shall be credited to each unit in accordance with that unit's interests in common elements. These credits shall be applied, unless the declaration provides otherwise, to the next monthly assessments of general common expenses against the unit under the current fiscal year's budget and thereafter until exhausted.
68 Pa.C.S. § 5313