How do I fix OHIP error code AO2?

Check the patient's obstetrical billing for this pregnancy, including other physicians. If the earlier service belongs to a previous pregnancy, check the service dates on both claims. If the initial service was already paid, bill the follow-up code that fits (for example P004 minor prenatal assessment instead of a second P003). 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 ClaimsManagement@ontario.ca with the Error Reports showing the original submission date.

When shouldn't I resubmit a AO2 claim?

The service was already paid once for this pregnancy and the limit is once per pregnancy.

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Error code

AO2 — Obstetrical service already billed

Q: What does OHIP error code AO2 mean?

AO2 means an obstetrical service that is limited per pregnancy was already billed for this patient. Check what was paid before resubmitting.

Obstetrical service already billed

An obstetrical service limited per pregnancy was already billed for this patient.

What to do: Check the patient's obstetrical billing for this pregnancy, including other physicians, then bill the follow-up code that fits.

Code: AO2
Description: Obstetrical service already billed

Explanation

Updated October 26, 2026

AO2 means an obstetrical service that is limited per pregnancy was already billed for this patient. Check what was paid before resubmitting.

What it means

AO2 means OHIP rejected an obstetrical claim because of a previous obstetrical service already on file. The Ministry's description is just 'Previous Obstetrical Service'.

Several obstetrical services are limited per pregnancy. The antenatal preventive health assessment (P005) is payable once per pregnancy. Medical induction or stimulation of labour may be claimed once per pregnancy by any one physician. A prenatal general assessment (P003) is payable after another general assessment only if the first wasn't to establish antenatal care (K2, K4).

Common causes

A second P005 for the same pregnancy
A prenatal general assessment billed when one was already paid for this pregnancy, by you or another physician
Medical induction billed twice in one pregnancy
A wrong service date that links the service to the wrong pregnancy

How to fix it

Check the patient's obstetrical billing for this pregnancy, including other physicians.
If the earlier service belongs to a previous pregnancy, check the service dates on both claims.
If the initial service was already paid, bill the follow-up code that fits (for example P004 minor prenatal assessment instead of a second P003).
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.

Don't resubmit if

The service was already paid once for this pregnancy and the limit is once per pregnancy.

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: O2, O3, O6, O7, O8