Having worked in pharmacy benefits (both processing online claims and checking benefits), most plans allow for an early refill due to a vacation. Let the pharmacy where you normally fill the rx process the online claim for a denial, and then tell them they need to call and request the indurance to give an early refill override for a vacation supply. Honestly the only time I ever had a problem was with a patient with Medicaid. Most other insurances have no problems with it. Also depending on the situation as another poster said you can refill after 75% of the meds (about 21-23 days depending on the plan) have been used by date it was last processed. What I always do when I do retail 30 day supplies is fill as soon as I can at the 21-22 day mark. I eventually get a nice little stockpile on hand, so I don't have to worry about needing to fill on vacation.