What code are you using for the 1 month follow up? E/M 99211-99215? If so, yes, you can bill a wellness and an OV on the same date. You need to have separate notes for each visit, and the 25 modifier is needed. Also, make sure the time portion is only for the part of the visit for that code. Seems obvious but not all catch that. For example if you have a total visit of 45 minutes, 20 on Wellness, and 25 on follow up, follow up visit should be coded only considering the 25 minutes spent.