Application of 401(a)(17) Compensation Limit to After-Tax Contributions

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Company X maintains a 401(k) plan permitting employees to contribute on an after-tax, pre-tax 401(k) or Roth 401(k) basis from 3% to 40% of compensation to the plan, except that HCEs cannot elect to contribute more than 10% on a pre-tax 401(k)/Roth 401(k) basis and up to an additional 3% on an after-tax basis. If an employee contributes a minimum of 3%, the company provides a matching contribution of 4%. Finally, if the employee's pre-tax 401(k)/Roth 401(k) contributions reach the 402(g) limit during the year, the employee is deemed to have elected to contribute after-tax contributions for the remainder of the plan year.

I have read the series of posts dealing with the application of the annual compensation limit on 401(k) and matching contributions. My question deals with after-tax contributions. Are they subject to the annual compensation or are they treated like 401(k) contributions? For example, let's say Executive A elects to contribute 3% of her compensation to Company X's 401(k) plan on a pre-tax basis and during 2006, her compensation is equal to $1 million. Once the employee's compensation reaches $500,000, she will have reached the 402(g) limit and all remaining contributions will be made on an after-tax basis. Can A contribute an additional $15,000 on an after-tax basis?

Assuming that Executive B earns $2 million during 2006 and elects to contribute 3% of his compensation on a pre-tax 401(k) basis. Once B's compensation reaches $500,000, he will reach the 402(g) limit of $15,000. Can B make after-tax contributions on the remaining $1.5 million up to $20,200 (15,000 + 8,800 + 20,200 = $44,000)?