In the case of a member or former member of the uniformed services of the United States, gross income does not include the amount of any reduction in his retired or retainer pay pursuant to the provisions of chapter 73 of title 10, United States Code.
In the case of any individual referred to in subsection (a), all amounts received as retired or retainer pay shall be excluded from gross income until there has been so excluded an amount equal to the consideration for the contract. The preceding sentence shall apply only to the extent that the amounts received would, but for such sentence, be includible in gross income.