He seemed to bear a grudge over the fact that most of the estate of his late brother was taken away by the wife of Motozane after his older brother Motozane passed away, and when TAIRA no Seishi and TAIRA no Shigemori died in 1179, he schemed with the Retired Emperor Goshirakawa and carried out a anti-Taira clan policy in order to confiscate the inherited land without a consultation with TAIRA no Kiyomori.
しかしかつて亡兄・基実の死後、その遺領の大半を基実の妻であった平盛子に奪われたことを恨んでいたらしく、基房は治承3年（1179年）に盛子と平重盛が死去すると、その遺領を平清盛に何の相談も無く、後白河法皇と謀って没収するという反平氏的政策を打ち出した。