Certified surgical tech

Please help!

I recently took on a new client who is a certified surgical tech. She is not licensed. I need to know the proper modifier to use for her services (80 vs 81)

I have submitted claims for her so far, that are being denied for modifier 80. So would it be appropriate to bill 81? I want clarification before I submit claims going forward.

Thank you...in advance for your help.

Certified surgical tech