Remark Code M38 on Your EOB — Meaning & What to Do

Remittance Advice Remark Code (RARC)

What remark code M38 means: This service requires prior authorization that wasn't obtained.
What to do about remark code M38: If you believe this is wrong, you can appeal with supporting notes from your doctor.

Remark codes add detail to a claim decision. They appear alongside the main adjustment codes on your Explanation of Benefits or remittance notice, giving the specific reason behind remark code M38.

Seeing remark code M38 on your EOB?
A denial code tells you what the payer reported, but it may not tell the whole story. Reviewing your EOB and bill together can help clarify what may need attention.

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Related codes

RARC M25The information doesn't support the need for this service. RARC M39This service isn't covered because it's considered routine. RARC M16Refer to the payer's bulletin or notice for more details. RARC M51The procedure code is missing, incomplete, or invalid.

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Frequently asked questions about Remark code M38

What does remark code M38 mean on my EOB?

This service requires prior authorization that wasn't obtained.

What should I do about remark code M38?

If you believe this is wrong, you can appeal with supporting notes from your doctor.

Seeing this code on your own EOB?
Upload the EOB, the bill, or both — MD Bill Check reads the codes on your documents, compares them side by side, and flags what's worth questioning. Free, no account needed.

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Last reviewed 2026-07-07 · MDBillCheck Editorial Team. Plain-English explanations are original wording; always verify the specific reason with your insurer.