Final answer:
401(k) plan matches and 403(b) plan matches require Form W-2 Box 12 reporting of employer contributions.
Step-by-step explanation:
The benefits that require Form W-2 Box 12 reporting of employer contributions are 401(k) plan matches and 403(b) plan matches.
Employer contributions to these retirement plans are considered supplemental pay and are reported in Box 12 of the employee's W-2 form with the code 'D'.
On the other hand, Health Savings Accounts (HSAs) and Health Reimbursement Arrangements (HRAs) are not subject to Form W-2 Box 12 reporting of employer contributions.