An annual nondiscrimination test for 401(k) plans that measures whether employee deferrals discriminate in favor of highly compensated employees (HCEs). Savings Incentive Match Plan for Employees 401(k) Plans (SIMPLE 401(k) plans) and safe harbor 401(k) plans are not required to perform the ADP test. For purposes of the ADP test, employee deferrals include pre-tax and Roth contributions, but do not include catch-up contributions.