Required Minimum Distribution (RMD) rules apply to 401(a) plans. An RMD is simply the minimum amount that an employee must withdraw annually in retirement. RMDs begin when someone reaches age 73* and is no longer working for that employer.
An individual must ensure they're withdrawing their full RMD; there are penalties for not doing so. In most cases, the retirement plan administrator will inform the employee what their RMDs are. You do not have to report that it is a 401A on your tax return.