For purposes of this section, the term “noncompliance period” means, with respect to any failure, the period beginning on the date the failure first occurs and ending on the date the notice to which the failure relates is provided or the failure is otherwise corrected.
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 any person subject to liability for the tax under subsection (d) did not know that the failure existed and exercised reasonable diligence to meet the requirements of subsection (e).
If the person subject to liability for tax under subsection (d) exercised reasonable diligence to meet the requirements of subsection (e), the tax imposed by subsection (a) for failures during the taxable year of the employer (or, in the case of a multiemployer plan, the taxable year of the trust forming part of the plan) shall not exceed $500,000. For purposes of the preceding sentence, all multiemployer plans of which the same trust forms a part shall be treated as 1 plan.
If an applicable pension plan is amended to provide for a significant reduction in the rate of future benefit accrual, the plan administrator shall provide the notice described in paragraph (2) to each applicable individual (and to each employee organization representing applicable individuals) and to each employer who has an obligation to contribute to the plan.
Except as provided in regulations, the notice required by paragraph (1) shall be provided within a reasonable time before the effective date of the plan amendment.
The Secretary may by regulations allow any notice under subsection (e) to be provided by using new technologies.