Denial of double benefit

No deduction shall be allowed under this section for any amount for which a deduction is allowable under any other provision of this chapter, or for which an exclusion is allowable under section 127 to the taxpayer by reason of the payment by the taxpayer’s employer of any indebtedness on a qualified education loan of the taxpayer. The deduction otherwise allowable under subsection (a) (prior to the application of subsection (b)) to the taxpayer for any taxable year shall be reduced (but not below zero) by so much of the distributions treated as a qualified higher education expense under section 529(c)(9) with respect to loans of the taxpayer as would be includible in gross income under section 529(c)(3)(A) for such taxable year but for such treatment.