I'll try and make it simple.
So everything we physicians do has a procedure code associated with it (a CPT code). Office visits, appendectomies, c-sections, autopsies, lacerations, amputations, everything. Each CPT code has a value associated with it, called a Relative Value Unit, or RVU. This determines how much Medicare (and private insurance) pays for a given code. An RVU is worth a certain amount of money to Medicare. Let's say its $100 per RVU.
So if a regular office visit is worth 1 RVU, Medicare will pay $100. Let's say an appendectomy is worth 6.5 RVUs. That means a surgeon would get paid $650 for doing one.
That said, an RVU does take overhead into account. So the RVU is broken down further into 3 sections: physician work (wRVU), practice expense, and malpractice. There are worth, in order, 52%, 44%, 2% of each total RVU.
So for that $100 office visit, Medicare expects a physician to earn $52 of that while $44 goes to office overhead and $2 goes to malpractice.
So if we go to the Medicare Fee Schedule (
Overview of the Medicare Physician Fee Schedule Search) and look up a 99213 which is the most common outpatient office visit code, in my area it is worth $70. So Medicare expects me to earn as pure income 52% of that, or $36.40. Its a 15 minute-type visit so I can do 4 in an hour which brings me to $145.6 per hour income by Medicare rules.
It gets more complicated as you get deeper into it, but that's the short version.