The Congressional Research Service has conducted an Analysis of Whether Linking Tax Benefits to the Geographic Variations in the Cost of Living Violates the Uniformity Clause:
Based upon an examination of the case law, it may be possible to identify scenarios in which geographical classifications in the exclusion of employer-provided health insurance would likely be permissible. But, because no tax has yet been found to violate the Uniformity Clause by the Court, it may not be possible to identify a clear line demarcating the scope of constitutionally permissible geographic classifications
