Except as provided in §B of this regulation, for each dwelling house located on a parcel for which agricultural use assessment is determined applicable, a minimum of 1 acre shall be designated as homesite and assessed at fair market value. If the amount of land serving the dwelling house as homesite exceeds 1 acre, that greater amount of acreage shall be assessed at fair market value. When a dwelling is located on a parcel under an FCMA of less than 6 acres, the Department may adjust the size of the homesite.