Third party appeals are typically made by neighbors or aggrieved individuals who are seeking to correct an error in the assessment of someone else's property. Errors can create inequities in the assessments of similar properties, so a lack of uniformity in assessments will often surface as the primary issue of a such an appeal. Appeals may also originate from tenants, who are challenging the assessment on leased properties. Regardless of the source or reason for the appeal, the property owner is usually unaware that his or her property is being appealed by someone else. It is therefore necessary that the Supervisor of Assessments send a letter notifying the property owner that his or her assessment has been appealed. It is not necessary for the property owner to attend the appeal hearing or to participate in the appeal process. Only in the instance where there is some compelling reason offered to substantiate an increase in the assessment would it be necessary to provide the property owner an opportunity to be heard. A separate hearing should then be scheduled for the owner, but only after the justification for the possible increase has been reviewed with the State Supervisor. There is no procedural due process requirement that both the third party and the taxpayer be present at the same hearing, and in most instances this would not be advisable.

Great care should be given to allow for an impartial review of the facts. Any new information that may be obtained in the appeal hearing should be recorded for use in the next assessment review. The Supervisor may not increase the value of the property unless authorized by the State Supervisor or otherwise ordered by the Property Tax Assessment Appeal Board or Maryland Tax Court.

When a final notice is sent that would increase the assessment from a third party appeal, the notice should be sent to the appealing party. A duplicate final notice should be sent to the property owner. Both the property owner and the appealing party would have an opportunity for further appeal.