Maryland Code, Tax-Property § 8-222

(b)(1) Subject to paragraph (2) of this subsection, if the supervisor finds that the land meets the criteria of § 8-221 of this subtitle, the land shall be assessed at the rate equal to farm or agricultural land under § 8-209 of this subtitle.

(2) In Howard County, for Howard County property tax purposes, a planned development land assessment is available for qualified land for no more than 20 consecutive years beginning with the taxable year following the calendar year in which the land initially qualifies under paragraph (1) of this subsection.