Flo and everyone - this is a perennial question.

Let's start with this - technically a prescription is not required to by normal or hypertonic saline solution. Based on this, most insurers, including Medicare will not allow you to use prescription benefits to pay for it. I KNOW - sometimes pharmacist and insurers let it "slip through" but they aren't required to.

Long story on Part B, but here goes (and I'm going to immediately repost to the ABC's of MAC & Bronchiectasis so I can point to it later.This was not my idea, and I wouldn't even begin to guess the logic, but here it is in a nutshell.

1) Any solution used in a nebulizer, or other piece of "durable medical equipment", is not covered by Part D Medicare but MAY be covered by Part B Medicare (other medical expenses) under certain conditions. Usually these are explained in long documents issued by Medicare.
2) Hypertonic saline (any solution above .9%) falls into this category.
3) The limitations, as I understand them are this: you must have been prescribed a nebulizer by Medicare for dispensing a prescription solution (other than saline.) Some plans also require that those prescription solutions are currently being dispensed. Silly thing - if I get my saline and levalbuterol at the same time, I pay $5, other wise my copay is around $15.
4) The pharmacy where you buy the saline must have a Part B contract with Medicare. Some chains dispense durable medical equipment and have such agreements, others do not (CVS in our area does not, but Walgreens and Walmart do.)
5) The pharmacy must submit the claim to Medicare Part B with the appropriate codes. And they must indicate on the initial prescription that you have a Medicare prescribed nebulizer. Please don't ask - I don't know them and cannot get them. Your copay will be reduced according to you Part B Medicare and any supplemental insurance you have, so you may pay 20% of retail, or 20% of the "allowable amount" or even zero under some plans.

If you are having issues with coverage, please reread. If you meet the requirements, consider checking with another pharmacy. Ande be sure to check out GoodRx.