(d) Amounts includable in gross income of employee when his rights under annuity contract change to nonforfeitable rights. Any amount which, by reason of
section 403(d) and after the application of paragraph (b) of
§ 1.403 (b)-1, is required to be included in an employee's gross income for the year when his rights under an annuity contract change from forfeitable to nonforfeitable rights shall be considered an amount contributed by the employee and shall be aggregated with amounts, if any, to which paragraphs (a), (b), and (c) of this section apply for the purpose of determining the aggregate amount of premiums or other consideration paid or contributed by the employee for such annuity contract. In other words, if, under
section 403(d), an employee of an organization exempt from tax under
section 501(a) or
521(a) is required to include an amount in gross income by reason of his rights under an annuity contract changing from forfeitable to nonforfeitable rights, such amount, to the extent it is not excludable from gross income under paragraph (b) of
§ 1.403 (b)-1, shall be considered an amount contributed by such employee for the annuity contract.