Its very easy. There are usually only 3 codes you should ever use - 99212, 99213, 99214. 99211 is nurse visit. 99215 is super complex and if you use too many Medicare will audit you. Now that being said, 90% of your visits should be level 4 and I'll explain why.
Its easiest to break it down by parts: HPI, exam, A/P. 2 of those 3 must be at the same level to bill at the highest. I never let exam dictate my coding level, so let's focus on the other 2.
First, always make sure your HPI meets level 4 criteria which for acute problems is 4 bullet points among the following: location, quality, severity, duration, timing, context, modifying factors, associated symptoms. Add 1 PMH/social point and 2 ROS systems and you're good. So: Patient comes in with 4 day (duration) history of nasal congestion with yellow phlegm (quality). Associated with cough (associated symptoms). OTC mucinex doesn't help (modifying factors). Pt is/is not a smoker (social). ROS: No fever and no dyspnea (2 systems). There, easy level 4 HPI.
For chronic problems you either need 2 stable problems or 1 unstable chronic problem. For example: HTN/hypothyroid with no complaints on either will get that. Alternatively, a COPD exacerbation will too.
Next is A/P. For acute/new problems, if you write a prescription you meet level 4 criteria. This could be as simple as a sinus infection that you give augmentin or something more like pyelo where you give cipro. Would also apply to an ankle sprain that you wrote Voltaren for. If you don't write a script, its level 3 (colds with no prescription, rash with OTC cortisone, tinea with OTC clotrimazole).
For chronic you either need 3 stable issues (HTN, DM, cholesterol) or 1 problem that needs tweaking (HTN BP not controlled) either because of not being well controlled or medication side effects - basically anything that means you need to change anything. Anything less than that is level 3.
The nice thing is that most level 3 visits can be tweaked to be level 4. URI can become sinus infection, and a script for flonase gives you a level 4. Your isolated controlled hypertensive is likely overweight/obese so there's your uncontrolled chronic problem if you actually address it (same if they smoke). If you use a prescription strength steroid cream for bug bites/poison ivy/eczema it becomes level 4. You get the idea.
