2 Corinthians 8:13 For I mean not that other men be eased, and ye burdened:

The encouragement by the Apostle Paul for the Corinthian church concerning their giving was not to put a financial strain upon them so that they would be impoverished and the Jerusalem church eased. [MacDonald]

The duty that the Apostle Paul presses upon the Corinthian church was to give according to their means. No doubt, their contribution may be more than the churches in Macedonia, he assured them it was a team effort with the other churches, the burden of the support is therefore shared. The principle is to give what they are able to with a willing heart and to complete the task.