Which test specifically assesses after-tax contributions?

The 401(m) test is designed to specifically assess the after-tax contributions made to a 401(k) plan, particularly the matching contributions that can be made in conjunction with employee contributions. This test evaluates the ratio of contributions made by highly compensated employees compared to non-highly compensated employees, ensuring that the plan maintains compliance with non-discrimination rules concerning after-tax contributions and matching.

By focusing on the contributions that are made after taxes, this test is integral to plan administrators who need to ensure employee benefits are equitably distributed and that the plan meets IRS regulations and requirements. The other tests mentioned, like the ADP test, focus more on pre-tax contributions and overall contribution limits rather than specifically on after-tax contributions.