Oh boy, these are always fun. I think this is right

r1 = DLOOKUP("NonFacilityRate","CMSCarrierLicenseRates2021AT","CarrierLocality=""" & L & """" & " AND LicenseLevel=""" & LL & """" & " AND HCPS=""" & C1 & """")

I personally do NOT like Variant data types except in a very few instances.  Variant can throw errors in my experience.  
My opinion is you should use the same data type in your Dim as the type of data you are bringing into that variable.

Access does a pretty good job of determining what the data type is BUT it can get it wrong.
This  could be the reason for your data type mismatch.

Scott is correct. I hate variants too... they should be on the Evil list. R1 should be Dim'd as whatever data type NonFacilityRate is in your table. Looks like the others are all strings. Do that. :)

THANK YOU SO MUCH! I removed the variants for everything except r1. Am I the only person that pumps my fists and cheers when the DB does what they want?! :D

From the name NonFacilityRate, I'm guessing that's a money value. Dim it as Currency.

Another question: Im pretty sure this could have been simplified, but I have this code listed out 15 times, so the user can search for up to 15 codes at once. My first version allowed for one at a time. Is there a way to exit the sub after the last code is entered? I tried if isnull(C2) or C2= then exit sub before the line of code for C2, but it didnt seem to help. The time it is taking to populate makes it seem like its still going through each line, even if there isnt a code entered.

Kristy you are obviously doing stuff that is pretty advanced.  I see by your badge that you have only started the Beginner Series.  Would you please give us a little background of your experience with Access, or programming in general, so we know how basic or not to make our answers.

If you are listing this code 15 times it should be in its own Sub procedure.

Here are some links to get you started:

Introduction to Access VBA

NZ Function

Access Search Seminar
Really look into the Search Seminar.  It is one that has stood the test of time and as a TechHelp member you get a discount on the course.  Refer to the email Richard sent you when you joined.

Hi Scott! My background: I took computer programming, Visual Basic,  classes in high school and really enjoyed it. I had one course in college that briefly touched on Access. During my last maternity leave, 9 months ago, I started watching Access videos and built two databases to help with my work. I like to work smarter, not harder :) Ive literally watched HOURS of videos on Access and have been able to do everything Ive wanted so far. Im now working on a database to be used by multiple departments. I feel that Im a quick learner, and I am good at mapping out what I want my databases to do. I just dont know how to make it all come together. I understand things at the simple level, but I want to challenge myself and make this database do more.

Long story short, Ive realized I really enjoy programming, but I know Im far behind. I started watching videos about Python coding, but I figured Id should complete this project before I try to learn a different language. :)

Thanks for that.  This will help a lot in answering future questions!