GoodRx can be used by people on Medicare, but not at the same time as Medicare. It works as an alternative, not an add-on. At the pharmacy counter, you choose one or the other for each prescription, and the pharmacist processes the transaction through whichever option gives you the lower price.
Why You Can’t Combine Them
GoodRx is not insurance. It’s a discount card that negotiates prices directly with pharmacies, completely outside the insurance system. Because Medicare Part D is a federal insurance benefit, pharmacies are required to process covered medications through your Part D plan first. You can’t stack a GoodRx discount on top of your Part D copay to bring it even lower.
What you can do is bypass your Part D plan entirely for a specific prescription and pay the GoodRx price instead. This is a separate, cash-price transaction. Your Part D plan isn’t involved at all, which has both advantages and trade-offs.
When GoodRx Beats Medicare
For common generic medications, GoodRx frequently undercuts Medicare Part D copays. To give you a sense of the difference:
- Atorvastatin (generic Lipitor): around $4 with GoodRx vs. a typical $10 Part D copay
- Lisinopril (a blood pressure medication): around $2 with GoodRx vs. $7 through Part D
- Metformin (generic Glucophage): around $3 with GoodRx vs. $5 through Part D
These savings are modest per fill but add up over a year of monthly refills. GoodRx also becomes especially useful for medications your Part D plan doesn’t cover at all. Medicare excludes certain categories of drugs, and GoodRx can provide a discount on those prescriptions where your insurance offers nothing.
The Deductible Trade-Off
Here’s the catch that trips people up: money you spend through GoodRx does not count toward your Medicare Part D deductible or your annual out-of-pocket spending. As far as Medicare is concerned, that purchase never happened.
This matters because of how Part D is structured. You pay more out of pocket in the early part of the year while meeting your deductible. Once you hit certain spending thresholds, your costs drop. Starting in 2025, Part D has a $2,000 annual out-of-pocket cap, after which you pay nothing for covered drugs for the rest of the year. Every dollar you route through GoodRx instead of Part D is a dollar that doesn’t push you closer to that $2,000 ceiling.
So if you take expensive brand-name medications that will push you toward the cap regardless, using GoodRx for your cheap generics could actually slow your progress and cost you more in the long run. On the other hand, if your total drug costs are low and you’ll never approach $2,000, saving a few dollars per prescription with GoodRx is straightforward savings with no downside.
How to Use It at the Pharmacy
The process is simple. Look up your medication on the GoodRx website or app before you go to the pharmacy. It will show you discounted prices at pharmacies near you, which can vary significantly from one store to another. Select a price and pull up the coupon, which includes a group number and ID that the pharmacist needs to process the discount.
At the counter, tell the pharmacist you’d like to compare the GoodRx price to your Part D copay for that prescription. Most pharmacists are happy to check both and let you choose the lower one. If you go with GoodRx, they’ll run it as a discount card transaction instead of billing your Medicare plan. You can make this choice on a drug-by-drug basis, so you might use Part D for one medication and GoodRx for another in the same visit.
Deciding Which to Use for Each Drug
The right choice depends on your overall medication picture for the year. For each prescription, compare the GoodRx price to your Part D copay. If GoodRx is cheaper, ask yourself whether the Part D spending on that drug would meaningfully help you reach your out-of-pocket cap. For someone taking only a few inexpensive generics, the cap is irrelevant and GoodRx savings are pure upside. For someone taking a costly specialty drug alongside several generics, funneling even the generic purchases through Part D gets you to the $2,000 cap faster, after which everything is free.
A practical approach: early in the year, tally up your expected Part D costs across all your medications. If the total will clearly exceed $2,000, use Part D for everything to reach the cap as quickly as possible. If your total costs will stay well below $2,000, use GoodRx wherever it offers a lower price and pocket the savings on each fill.