The gross estate shall include the value of an annuity or other payment receivable by any beneficiary by reason of surviving the decedent under any form of contract or agreement entered into after
Subsection (a) shall apply to only such part of the value of the annuity or other payment receivable under such contract or agreement as is proportionate to that part of the purchase price therefor contributed by the decedent. For purposes of this section, any contribution by the decedent’s employer or former employer to the purchase price of such contract or agreement (whether or not to an employee’s trust or fund forming part of a pension, annuity, retirement, bonus or profit sharing plan) shall be considered to be contributed by the decedent if made by reason of his employment.