Error code
AT1 — Only One Modality Allowed
Two virtual modality codes
The virtual care claim carries more than one modality indicator; each claim must have only K300A (video) or K301A (phone).
What to do: Keep only the indicator for the modality used for most of the visit, and resubmit.
- Code
- AT1
- Description
- Only One Modality Allowed
Explanation
Updated October 26, 2026
AT1 means the virtual care claim has more than one modality indicator. Keep only K300A (video) or K301A (phone) and resubmit.
What it means
AT1 means a comprehensive virtual care claim was rejected because it carried more than one modality indicator. Each claim must identify the technology used: K300A for video or K301A for telephone (audio only) (A70).
If the modality changed during the visit, for example a phone call that became a video call, only the service by the modality used for more than 50% of the time is payable. For time-based services, the time in both modalities is added together to count units (A69).
Common causes
- Both K300A and K301A on the same claim
- The visit switched between phone and video and both were billed
How to fix it
- Check the chart for the modality used and, if it changed, which one was used for most of the visit.
- Keep only that modality indicator on the claim.
- Resubmit the corrected claim within three months of the service date if you can. If that window has passed but the claim was first submitted on time, use the Ministry's stale-dated resubmission process: one stale-dated claim file through MCEDT, then an email to [email protected] with the Error Reports showing the original submission date.
How APEX handles it
APEX reads your error reports and remittance advice from MCEDT and lists claims rejected with this code in its Correction Centre for you to correct and resubmit. See how APEX works · Pricing
Related codes: AT2, AT4, VT1, VTC