I always understood that that a 402(g) excess deferral could not be withdrawn after 4/15. For example, if a 30-year-old participant deferred $18,000 during 2010, then the excess $1,500 must be refunded by 4/15/11. Otherwise, it stays in the plan and gets taxed again when it is withdrawn due to some future distributable event. Regardless of whether the excess is withdrawn by 4/15/11, the participant will be taxed on the $1,500 in 2010 since his personal tax return can only allow a $16,500 deduction.