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WSIB Opioid Assessment Form: Physician Fee Code M639

The WSIB requests this form when it needs information on the medical indications and therapeutic benefit of a patient's prescription opioids for a work-related injury or illness. It supplies the form rather than posting it for download, and the physician completes it and returns it for a set fee under code M639. It sits within the WSIB's opioid management rules on authorization and long-term therapy.

Who completes it

The physician completes the whole form and returns it to the WSIB.

Submitting and payment

How to submit it
Complete the copy the WSIB supplies and return it to the WSIB; if you fax it, the physician fee schedule says not to also send the original.
Who pays
The WSIB pays the physician directly under fee code M639, the opioid assessment form code in its physician fee schedule.

Good to know

  • All opioids with a morphine equivalent dose greater than 90 require WSIB authorization, and opioid coverage beyond four weeks is subject to clinical review.
  • For long-term opioid prescriptions, the WSIB requires an opioid treatment agreement between patient and prescriber, and one prescriber and one pharmacy for all opioid prescribing.
  • To request opioid coverage outside the formulary, prescribers use Part B of the Medication exception form (10880A), which is also paid under M639.
  • The WSIB can refer prescribers to its Occupational Health Assessment Program for help with tapering or switching opioids or managing opioid use disorder.

Get the official form

Download the current version from the source each time; forms change without notice.

Opioid assessment form

Official page

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How this list is checked

A form is listed only after its name and number were confirmed on the issuing agency’s or insurer’s own website, or in the form itself. Each entry links to that source. The list was last checked in October 2026. Forms change without notice, so download the current version from the official page before you fill it in.

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Frequently asked questions

When does the WSIB send an opioid assessment form?

The WSIB physician fee schedule says the form is requested when the WSIB needs information on the medical indications and the therapeutic benefit associated with a patient's prescription opioid drugs. The form is not posted for download; complete the copy the WSIB provides and return it to the WSIB.

What is WSIB fee code M639?

M639 is the WSIB physician fee schedule code for the opioid assessment form. The current Medication exception form (10880A) also uses M639 for its Part B opioid treatment request, while Part A, the non-opioid request, is paid under M758. Accounts received more than six months after the service may be reduced.

What does the WSIB monitor in long-term opioid therapy?

Its opioid page says long-term prescriptions need an opioid treatment agreement between the patient and prescribing physician, with one prescriber and one pharmacy for all opioid prescribing. The WSIB monitors for opioids used together with benzodiazepines or other psychiatric drugs, and supports free naloxone kits for people on chronic opioids at risk of overdose.