Plan imposes a deferral limit for the year. Participant defers less than that limit during a portion of the year. Can this participant contribute a higher percentage than the plan imposed limit for the remaining portion of the year so that the total deferrals for the year in the aggregate do not exceed the plan imposed limit as a % of total compensation?

Depends on whether there is a plan-imposed election period. I've not used election periods, but some might. Especially large plans.

Does the plan specify % on payroll basis or annual basis. If stated as 10% annual then they could do 5% for a while and 14% for a while, as long as they don't exceed annual rate. If the plan specifically - as all four of ours do - that % if calculated on payroll basis then they are out of luck.

Thanks, I have another question regarding determining catch-ups for plan imposed limits. The ERISA outline books discusses summing up the limits for each compensation period included in the plan year or using a weighted average.

Can someone explain how the two methods might be different?

Maybe I don't understand the question, but the catch up is $4,000 for 2005 regardless of the plan limit.

Example - plan limit is 10% and person makes $75,000. Plan limit for them is $7,500 and catch up is $4,000.

Plan limit is 50% makes the numbers $14,000 and $4,000.