employer for the taxable year a tax equal to 10 percent of the aggregate required contributions to such automatic deferral IRA for all plan years that are not paid by the date specified in section 408B(c)(4)(A)(i) and that remain unpaid as of the end of any plan year ending with or within the taxable year. (b) Additional tax If a tax is imposed under subsection (a) on any unpaid required contribution and such amount remains unpaid as of the close of the taxable period, there is hereby imposed a tax equal to 100 percent of the unpaid required contribution to the extent not so paid or corrected. (c) Limitations on amount of tax (1) Tax not to apply where failure not discovered exercising reasonable diligence No tax shall be imposed by subsection (a) on any failure during any period for which it is established to the satisfaction of the Secretary that the employer did not know, and exercising reasonable diligence would not have known, that such failure existed. (2) Tax not to apply to failures corrected within 30 days No tax shall be imposed by subsection (a) on any failure if— (A) such failure was due to reasonable cause and not to willful neglect, and (B) such failure is corrected during the 30-day period beginning on the 1st date the employer knew, or exercising reasonable diligence would have known, that such failure existed. (3) Waiver by Secretary In the case of a failure which is due to reasonable cause and not to willful neglect, the Secretary may waive part or all of the tax imposed by subsection (a) to the extent that the payment of such tax would be excessive relative to the failure involved. . (c) Preemption of conflicting State laws Any law of a State shall be superseded if it would directly or indirectly prohibit or restrict an employer from creating or maintaining an automatic deferral IRA (as defined in section 408B of the Internal Revenue Code of 1986). (d) Clerical amendment (1) The table of sections for subpart A of part I of subchapter D of chapter 1 of the Internal Revenue Code of 1986 is