A Maryland Notice of Disallowance is a document issued by the Maryland Comptroller's office to inform taxpayers that a deduction, exemption, credit, or other item of income has been disallowed on an individual or business income tax return. The notice states the amount of tax due as a result of the disallowance, and may provide instructions on how to appeal the decision. There are two types of Maryland Notice of Disallowance: Notice of Disallowance, and Notice of Disallowance for Unreported Earnings. The Notice of Disallowance is used when the Comptroller's office determines that a deduction, exemption, or credit has been erroneously claimed, while the Notice of Disallowance for Unreported Earnings is used when the Comptroller's office determines that income has been omitted from a return.