If a person disposes of ordinary income, the amount of the disposition is the amount that, in the Commission's opinion, is:
(a) if the person receives no consideration for the diminution in the rate of the person's ordinary income--the annual rate of the diminution of the person's ordinary income; or
(b) if the person receives consideration for the diminution in the rate of the person's ordinary income--the annual rate of the diminution less the part (if any) of the consideration that the Commission determines, in writing, to be fair and reasonable in all the circumstances of the case.