Several other issues exist when switching carriers . Going from a non deductible or lower deductible plan to a deductible rx plan . Any difference in tier levels on drugs . More so on future tier 3 and above drugs . Just had a client flipped from a no rx deductible tier 3 and flat copays to a company with $590 rx deductible and 25% tier 3 copay . They wanted $800 on her tier 3 drug 1 week ago first fill . I moved her back to old plan for 5-1I have not seen this in action yet and not promised this to a client but my understand is that the part d deductible amount met transfers over to new plan even with different carrier .This includes both the amount paid by consumer and the insurance company.