HCE deferred in excess of 402g limit - does it affect ABPT testing?

Great question!

The EOB says in Chapter 8 Coveage Testing Part C., Average benefit percentage test, 2. Computing benefit percentages, 2.i. Certain distributed amounts must be included in benefit percentage:

2.i.2) Corrective distributions of excess deferrals under IRC §402(g). Whether to apply the rule described in 2.i.1) to excess deferrals under IRC §402(g) is less clear. Treas. Reg. §1.415(c)-1(b)(2)(ii)(D) provides that excess deferrals which are distributed by the April 15th deadline under IRC §402(g)(2) are not treated as annual additions for §415 purposes. However, Treas. Reg. §1.402(g)-1(e)(1)(ii) provides that the excess deferrals of nonhighly compensated employees (NHCs) are excluded from the nondiscrimination test (i.e., the ADP test) under §401(k), but the excess deferrals of the highly compensated employees (HCEs) are included in the ADP test. With the difference in treatment between HCEs and NHCs for nondiscrimination testing purposes, it is recommended that excess deferrals made by HCEs be included in the benefit percentage, even if they are distributed by the April 15th deadline.

The short version of the logic that leads to this conclusion is it the excess is included in the ADP test, the excess should be included in the ABT.

Note that the analysis admits that this is "less clear" and the conclusion is "recommended" which will leave up to the plan and the practitioner to decide if they embrace this interpretation.  The most conservative approach is to include the excess deferrals.