I have a question that I am unable to find an answer to. I am always directed back to the CMS guidelines but it is not answering my question.

How many times can the modifier(s) GC or GE be used on a single encounter? If the patient is seen for a visit (99213, etc.) The physician bills the e/m and adds the corresponding modifier GC or GE to it and in addition to the e/m the resident does a procedure or multiple procedures under the direction of the attending during the same visit (20610, etc.). Would I add another GC modifier to the procedure code?
Is this what would be submitted;
99213-25, GC
20610-GC

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