Once eligible always eligible for deferrals?

Once an employee has satisfied the initial eligibility computation period what if he goes under the 1,000 hours for the next plan year? Do you have to do a corrective distribution of his deferrals? Or is it, that if an employee was eligible to defer at one time they they will always be eligible to defer? All I see in the plan document is that "An employee is eligible to participate if he satisfies the following requirement during the Eligibility computation period". It says that you must meet the 1,000-hour requirement to be able to defer but it doesn't mention after you've met eligibility requirements you must have 1,000 hours in the plan year to be able to defer. 

I appreciate anyone's thoughts!

For starters, the vast majority of 401(k) plans are written so that once an employee is eligible to make salary deferrals, then the employee will continue to be able to make salary deferrals.  At the end of the day, the plan document governs so you will need to read it carefully to confirm your conclusion.

Now let's dive into the deep end of the pool.  Plans have three sets of service rules: eligibility, vesting and benefit accrual.  While the rules all may talk about hours, computation periods, time periods, breaks in service, rules of parity and such, each set of rules can be different.  Further, the applicable rules may be different for each source of contributions (e.g. deferrals, match, profit sharing...) Your question is refers to deferrals and to two of the sets of rules: eligibility and benefit accrual.  We assume the employee also has meet any entry date requirements.

The employee's having satisfied the eligibility rules in the employee's initial eligibility computation period means the employee is eligible to make deferrals.  That eligibility will continue year over year unless the plan has rules that would take away that eligibility.  These are the rules of parity and they typically come into play when an employee has when an employee terminates employment and subsequently is rehired.  That is not the case here, so the employee remains eligible to make deferrals.

A rule that an employee must work 1000 hours to be eligible to receive a contribution is a benefit accrual rule.  Typically, benefit accrual rules apply to the match or profit sharing contributions, and do not apply to deferrals.

Note, that if the plan has a provision that excludes an employee from based on a classification, the an employee who met the eligibility requirements and was deferring would not be able to defer if the employee's classification changed to an excluded class of employees.  An example of this would be a plan that excluded union employees from participation in the plan.  If a non-union employee was eligible and deferring in the plan became a union, then that employee would no longer be able to participate.

Again, read the plan document, and focus on the rules for eligibility to make deferrals.

Thank you!