Mansion-House Rule Law and Legal Definition

Mansion house rule is a principle applied in property tax matters. It provides that where a tract of land is divided by a county line, the whole tract is assessable in the county in which the mansion house is located. The rule is aimed at preventing the mischief which would flow from contests between the assessors of adjoining municipal divisions, respecting the right and duty of assessing property intersected by the division lines of districts. It guards against the low valuation which assessments of an entire property in parcels tended to produce. The Mansion House Rule applies to individual tracts of land depending upon their particular use.

The Mansion House Rule as applied to a single tract does not carry over to all of the smaller parcels, which are created by a subdivision of that original tract.[ Ekin v. Board of Comm'rs, 93 Pa. Commw. 528 (Pa. Commw. Ct. 1985)]