My doctor just asked me how/if he can bill for the time he spends on reviewing and signing labs, test results, etc. for patients that are in home health, assisted living, nursing homes, etc. I see the codes 99339,99340 and 99374-993820 and i find them a bit confusing as to which to choose. He would like to know the rules of who can bill and what documentation is needed and how he figures out the time spent. where can i find this information? any help would be appreciated.