According to SCOTUSblog, SCOTUS has granted cert in _Comptroller of the Treasury of Maryland v. Wynne_ where the issue presented is: "Whether the United States Constitution prohibits a state from taxing all the income of its residents -- wherever earned -- by mandating a credit for taxes paid on income earned in other states."
It's a little more complex than that. Maryland imposes both state and county income taxes. Out of state income tax is credited against the state tax, but not the county tax.
The court below held that violated the Commerce Clause. The Solicitor General in amicus says it doesn't, and that if people don't like the taxes imposed by the state or county in which they live, the remedy is through the political process, not the courts.
BeanSmart website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.