State personal income taxes are an important source of state tax revenue.1 However, these taxes impose significant and potentially expensive requirements on employers throughout the United States, requiring employers to accurately and timely withhold and pay these taxes to state and local governments. Although complying with the witholding requirements in an employee’s state of residence often is routine, complying with nonresident state and local withholding requirements associated with traveling employees is complicated at best and impossible at worst. Given the increase of traveling employees of companies of all sizes, there has been much discussion about the appropriateness of these complex withholding rules. It is time to reform and simplify employee withholding requirements. Further, the simplification effort should make consistent the liabilities imposed on employers and employees. This article examines the grounds for matching employers’ withholding obligations with nonresident employees’ personal income tax return filing obligations. We conclude that meaningful multistate uniformity efforts must provide that the obligations have identical thresholds because of the numerous complexities surrounding multistate withholding compliance.2