Nonresident reciprocity.

All payments received by natural persons domiciled outside Wisconsin who derive income from the performance of personal services in Wisconsin shall be excluded from Wisconsin gross income to the extent that it is subjected to an income tax imposed by the state of domicile; provided that the law of the state of domicile allows a similar exclusion of income from personal services earned in such state by natural persons domiciled in Wisconsin, or a credit against the tax imposed by such state on such income equal to the Wisconsin tax on such income.