Emergency billing turns on when the patient was seen. The multiple systems assessment code itself changes by time band — weekday day, Monday–Thursday evening, Friday evening and weekend, and nights — so the same clinical encounter carries a different fee depending on the hour. Add critical care units where the time is documented, and the ECG professional component where you interpreted one.
IntelAGENT derives the assessment code and eligible premiums from the service date and time, including shifts that cross a time band. See how →
Emergency billing follows a consistent pattern: the clinical decisions are not the hard part, the time arithmetic is. A single overnight shift can span three time bands, and the code that applies changes at each boundary.
The codes and what they pay
| Code | Description | Fee |
|---|---|---|
| G395A | Critical care, first 15 minutes | $64.70 |
| G391A | Critical care, each subsequent 15 minutes | $34.35 |
| H103A | Multiple systems assessment — weekday daytime | $46.65 |
| H153A | Multiple systems assessment — Friday evening, weekend, holiday | $69.60 |
| H133A | Multiple systems assessment — Monday to Thursday evening | $61.50 |
| H122A | Comprehensive assessment — nights | $99.60 |
| H123A | Multiple systems assessment — nights | $80.95 |
| H124A | Re-assessment — nights | $39.80 |
| H134A | Re-assessment — Monday to Thursday evening | $30.05 |
| H154A | Re-assessment — Friday evening, weekend, holiday | $34.15 |
| H152A | Comprehensive assessment — Friday evening, weekend, holiday | $85.70 |
| H105A | Interim admission orders, inpatient | $29.05 |
| H104A | Emergency department equivalent of a minor assessment | $22.75 |
| G313A | Electrocardiogram, professional component | $4.55 |
Fees are from the OHIP Schedule of Benefits and are the ministry's, not ours — they are the same for every billing provider. Always confirm against the current Schedule, and confirm eligibility rules and any companion requirements there too before billing a code you have not used. These fees are from the Schedule effective July 1, 2026 (PDF).
The time bands are the whole game
Unlike most of the Schedule, emergency assessment codes do not work as a base code plus a premium. The time band is baked into the code. H103A and H153A describe the same assessment; the difference is that one happened on a Tuesday afternoon and the other on a Saturday.
That design has two consequences:
- A shift crossing a boundary uses more than one code. An overnight shift starting Friday evening produces claims under the Friday-evening code and the nights code, split at the boundary, not one code for the whole shift.
- Getting the band wrong is invisible on the Remittance Advice. Billing the weekday code for a Saturday patient pays — just less. Nothing is rejected, so nothing tells you.
This is the single largest avoidable loss in emergency billing, and it is the clearest case for not choosing the code at all. IntelAGENT derives the band from the service date and time on the claim, splits a shift that crosses a boundary across the codes it actually falls under, and does it the same way on every claim — including the ones entered at 3am at the end of a long shift.
Critical care units
G395A covers the first 15 minutes of critical care; G391A covers each subsequent 15-minute unit. The time must be documented and must have been devoted to that patient.
Two failure modes, in opposite directions:
- Under-claiming. A 70-minute resuscitation documented as such supports G395A plus three units of G391A. Claiming G395A alone because the units were not counted is common and costs more than any other single omission in the specialty.
- Over-claiming. Units beyond what the record supports get rejected or recovered on audit. The documented time is the ceiling.
Before submitting critical care: the documented start and end time should divide into the number of units claimed, and the note should make clear the time was devoted to that patient and not shared across the department.
Special visit premiums
Special visit premiums are a separate mechanism from the time-band assessment codes, and they come up when you are called in rather than when you are on a scheduled shift. The rules on which premium applies, how many can be claimed for one visit, and which companion codes are required are set out in the Schedule and are specific enough that guessing produces rejections.
We have written the structure up separately rather than publishing a premium-code table, because the eligibility conditions matter more than the codes: how special visit premiums work.
What gets missed
-
Time-band codes on shifts that cross midnight
Patients seen at 23:50 and 00:10 are different codes. Manual entry almost always bills both the same way.
-
Critical care units against documented time
Count the units from the chart, not from memory at the end of the shift.
-
The ECG professional component
$4.55 is small. Across a year of shifts it is not, and it is a pure omission — you did the interpretation either way.
-
Interim admission orders
H105A exists for the work you do writing orders on a patient who is admitted but still in your department.
Billing the emergency department in IntelAGENT
Emergency billing is decided by the clock. Codes that depend on the time of service should come from the time of service.
The parts that matter for emergency practice:
- Time-derived codes. The assessment code and eligible premiums follow from the service date, time and facility rather than from a dropdown you have to get right.
- Health card validation. Version-code mismatches are a leading rejection cause in emergency departments, where cards are swiped under pressure. Validation happens before submission — see health card validation.
- Mobile entry. Billing a shift from the phone app, including scanning the card, rather than from a desk afterwards.
- Group and departmental billing. If the department bills as a group, remittances split back to the rendering physician — groups and departments.
- Rejections. Explanatory codes are surfaced with the reason and the correction path rather than as a raw RA — see claim rejections.
Three months free, then 0.25% of paid claims, capped at $39.99 a month. IntelAGENT has submitted OHIP claims since 2016 for more than 2,000 Ontario physicians.
Frequently asked questions
Which OHIP codes do emergency physicians bill most?
The multiple systems assessment family (H103A, H153A and the evening and night variants), critical care units G395A and G391A, and the ECG professional component G313A. Which assessment code applies is determined by the time and day of the encounter, not by the complexity.
How do emergency department premiums work?
The assessment code itself changes with the time band — weekday day, Monday to Thursday evening, Friday evening, weekend and holiday, and nights — rather than a base code plus a separate premium. Special visit premiums are a different mechanism and apply when you are called in.
How is critical care time billed in the emergency department?
G395A covers the first 15 minutes of critical care and G391A each subsequent 15-minute unit. The time has to be documented and devoted to that patient. The units are the common source of rejections, because the recorded time has to support the number claimed.
What gets missed most in emergency billing?
Time-band assessment codes on shifts that cross midnight, critical care units under-claimed against documented time, and the ECG professional component. All three are omissions rather than errors, so nothing on the Remittance Advice tells you they happened.
Related reading
Special visit premiums
How the premium mechanism works and when it applies.
GuideReduce missed billings
The omissions that never show up as rejections.
SpecialtiesAll specialties
Billing patterns by specialty.
ProductIntelAGENT on mobile
Bill the shift from the department, while the times are still right.