51 pages. Excerpt: Sections 401(k)(13), 401(m)(12), and 414(w), and the amended provisions of sections 411(a)(3)(G) and 4979(f), are effective for plan years beginning on or after January 1, 2008. These regulations are proposed to be effective for plan years beginning on or after January 1, 2008. Taxpayers may rely on these proposed regulations for guidance pending the issuance of final regulations. If, and to the extent, the final regulations are more restrictive than the guidance in these proposed regulations, those provisions of the final regulations will be applied without retroactive effect.