While it might seem confusing at first glance, the Formulary is not that difficult to figure out. On closer inspection, it is allocated into different tiers and those tiers have different costs. They not only have different costs, but you should pay attention to the fact that not every plan you buy is the same when it comes to tiers.
Some plans have more tiers, and some may have less. And then, there are circumstances where you might be given a drug to take that is in a tier higher than where you are, because that is what the doctor gave you. In cases like this, file an exception.
There are also coverage rules where certain drugs are used the right way and only when needed. If you aren’t sure how the Formulary and coverage rules work, talk to your local health insurance agent.