Add-on codes
An add-on code is never billed alone — it only pays alongside an acceptable primary procedure. Which primaries are acceptable, and sometimes whether the add-on is recognized at all, is set by CMS and can differ by payer.
Same visit, same extra 20 minutes — and the add-on code depends entirely on who is paying.
A level-5 office visit (99205 or 99215) runs long. The prolonged time is billable — but there is no universal code for it. Commercial and Medicare disagreed on the math, so each recognizes a different add-on and denies the other.
AMA · CPT
The AMA add-on for prolonged time on a high-level office visit. Commercial payers that follow CPT accept it with 99205 or 99215.
On a Medicare claim it denies — CMS assigns it status I (invalid) and does not recognize it.
CMS · HCPCS
CMS rejected the AMA's time thresholds and built its own add-on. Medicare requires G2212 — billed only with 99205 or 99215 — for the same prolonged time.
On a commercial claim it usually denies — most non-Medicare payers do not recognize the G-code.
The engineering takeaway:an add-on rule is not universal. The same claim is correct or denied depending on the payer, so the edit logic has to branch on payer before it decides the code — +99417 for commercial, G2212 for Medicare, each denied on the other.
Look up either code below to see its acceptable primaries in the current NCCI add-on file. Try 99417 or G2212.
Look up an add-on code
Enter an add-on to see its acceptable primaries, or a primary to see which add-ons list it. Try 99417 or G2212.
An add-on code may only be billed alongside an acceptable primary procedure. Enter either side — the add-on to see what it may accompany, or a primary to see which add-ons it supports.
25 checks per day, free and without an account. Need more, or want to call this from your own system? Request an API key — keyed access is unlimited.