RARC M79: Missing, Incomplete, or Invalid Charge
RARC M79 means the charge amount on the claim line is missing, incomplete, or invalid — a $0.00 or blank charge, a negative amount, or line charges that do not sum to the claim total. It rides with CO-16 and is fixed by correcting the charge and resubmitting.
- Type
- Informational (supplemental)
- Usually paired with
- CO-16
- Fixable?
- Yes — always
- Typical fix
- Enter a valid charge on every line; rebalance totals; resubmit
What does remark code M79 mean?
Official X12 text: "Missing/incomplete/invalid charge." Somewhere on the claim a money field failed: a line went out with no charge, a zero, a negative, or totals that do not reconcile. The payer cannot adjudicate a line it cannot price, so the claim returns unprocessed.
ERA mini-example: a flu-shot visit bills 90686 at $22.00 and admin code 90471 at $0.00 because the new vaccine admin fee never got loaded. The 90471 line denies CO-16 with M79. The charge master had the vaccine priced but the admin row blank — a two-minute fix that had been silently killing every flu-clinic claim for three weeks.
Which denial code does M79 come with?
Essentially always CO-16 — the unprocessable-claim CARC. There is no adjudication to appeal because the payer never evaluated coverage; the claim failed data validation. When you see the pair, go straight to the charge fields. Verify any unfamiliar combination in the denial code lookup.
How do you fix an M79 denial?
- Open the claim and inspect every service line charge: no blanks, no zeros, no negatives, two decimals.
- Confirm units are correct — a valid charge with zero units fails the same edit at some payers.
- Rebalance: line charges must sum to the claim total after any system rounding.
- Fix the source — the chargemaster row or fee schedule entry that produced the empty charge — then resubmit.
How do you prevent M79?
M79 is a charge capture hygiene problem. Price every new CPT/HCPCS code in the chargemaster before its first use — new vaccines, new-year codes, and newly added services are where blanks appear. Add a scrubber rule blocking any claim with a line charge of zero unless the payer explicitly requires informational lines. With those controls, M79 should be one of the rarest remark codes on your remits.
Frequently asked questions
Rarely. A few programs require zero-charge informational lines (some vaccine and encounter-rate billing), but most payer systems treat a $0.00 or blank charge as invalid and bounce the line with M79. If a payer wants an informational line, its companion guide will say so explicitly — default to a real charge everywhere else.
Formatting and math. Negative amounts, more than two decimal places, charges with characters in the field, a unit count of zero against a positive charge, or service-line charges that do not add up to the claim-level total all fail validation. Clearinghouses catch most of these, so persistent M79 usually points to a mapping bug in the billing system export.
No. M79 is purely structural — the field failed validation. Payers do not use M79 to argue your fee is too high; that conversation happens through CO-45 contractual reductions against the allowed amount. Fix the field, not the fee schedule.
Sources & further reading
Reviewed by the ImmediCare Solutions RCM team
Certified billers and coders handling claims across 50+ specialties nationwide. This entry is reviewed against current payer policy and CMS rules. Last review: Jul 5, 2026.
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