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M135 Remark Code: Plan of Treatment Missing or Invalid

M135 means the plan of treatment was missing, incomplete, or invalid. Payers require a treatment plan for certain ongoing services, such as therapy, to confirm they are planned, goal-directed, and covered.

Quick facts

Code
M135 (RARC M135)
Status
Active In use since January 1, 1997; last modified February 28, 2003.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The service was not paid due to missing or defective treatment plan information. The provider supplies it; the patient is not billed.
Official description
Missing/incomplete/invalid plan of treatment.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What M135 means

Ongoing services are often covered only if they follow a written plan with measurable goals and a defined frequency and duration. M135 tells you the payer needed that plan of treatment and either did not receive it, or received one that was incomplete or invalid.

M135 is broader than M141, which is specific to a missing physician-certified plan of care. M135 can apply to any treatment plan the payer requires.

Common causes

  • Therapy claims submitted before the plan was completed or signed.
  • A plan missing elements such as frequency, duration, or goals.
  • Plan dates that do not cover the date of service.
  • A plan sent without patient or claim identifiers.
  • An updated plan not sent after the original expired.

How to fix it

  1. Pull the current plan for the patient and check it against the payer’s required elements.
  2. Complete missing elements and obtain required signatures or certifications.
  3. Confirm the plan’s dates include the date of service.
  4. Submit the plan through the payer’s documentation process and resubmit or request reprocessing of the claim.

How to prevent it

  • Use plan templates that include every element the payer requires.
  • Track plan expiration dates and schedule recertifications before they lapse.
  • Hold therapy claims until a signed, current plan is on file.

See authorization and referral prevention for related pre-service requirements.

Codes that may appear with M135

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim lacks information, identified by M135 as the plan of treatment.
  • CO-252 (An attachment/other documentation is required to adjudicate this claim/service.): Documentation is required before the service can be adjudicated.
  • M141 (Missing physician certified plan of care.): The physician-certified plan of care was missing.
  • N238 (Incomplete/invalid physician certified plan of care.): The physician-certified plan of care was incomplete or invalid.
  • N351 (Service date outside of the approved treatment plan service dates.): The service date is outside the approved treatment plan dates.

M135 FAQ

Which services need a plan of treatment?

Commonly therapy services such as physical, occupational, and speech therapy, plus some behavioral health and home health services. Requirements vary by payer.

What should a plan include?

Usually diagnoses, long-term goals, the type, amount, frequency, and duration of services, and the provider's signature and date. Some payers require certification by a physician or other practitioner.

Does the plan have to cover the date of service?

Yes. Services outside the plan's certified dates may be denied under a different remark.