13(1)Where at any time compensation becomes payable under this Part, or became payable under Part II of the 1954 Act or Part VI of the 1962 Act or Part VII of the 1971 Act, in respect of depreciation of the value of an interest in land by a planning decision, then, for the purpose of determining whether that land or any part of it has or had an unexpended balance of established development value at any subsequent time—
(a)the amount of the compensation shall be deducted from the original unexpended balance of established development value of that land, and
(b)the original unexpended balance of that land or that part of it shall be treated as having been reduced or extinguished accordingly immediately before that subsequent time.
(2)Where an amount has become recoverable under section 133 in respect of the compensation specified in a compensation notice, except where, and to the extent that, payment of that amount has been remitted under section 134, for the purpose of determining any question as to the unexpended balance of established development value of any land at any subsequent time, so much (if any) of that compensation as is attributable to that land shall be treated as not having become payable, and accordingly (notwithstanding anything in sub-paragraph (1)) shall not be deducted from that balance.