Maryland’s personal income tax on State residents consists of a State income tax and a local tax (for the counties and Baltimore City). Residents who pay income tax to another state were allowed a credit against the State income tax, but not against the local tax. The Supreme Court determined  that this taxing scheme was unconstitutional because it discriminated in favor of intrastate over interstate economic activity in violation of the dormant Commerce Clause. The Court found this inherently discriminatory as it operates as an impermissible tariff against residents who earn income in interstate commerce.

Amended returns must be filed within three (3) years from the time a return was filed or two (2) years from the time the tax was paid, whichever is later. You must file a separate claim for each tax year in which you are requesting a refund. Properly filed protective claims previously filed with the Comptroller pending the outcome of the litigation will also be processed.