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N443 Remark Code: Missing or Invalid Total or Start/End Time

N443 means the total time, or the begin and end time, for the service is missing, incomplete, or invalid. Time-based services such as anesthesia need time reported so the payer can calculate payment, and the claim either lacked it or reported it in a way the payer could not use.

Quick facts

Code
N443 (RARC N443)
Status
Active In use since July 1, 2008.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The service could not be priced without valid time data. The provider supplies it; the patient is not billed.
Official description
Missing/incomplete/invalid total time or begin/end time.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N443 means

For a time-based service, the payer’s payment calculation depends on how long the service lasted. N443 says the payer could not find usable time data, either the total time or the start and stop times, depending on what it requires. Anesthesia claims are the classic case, but some payers apply the same logic to other services billed by time.

N443 generally appears with CARC 16.

Common causes

  • Units entered instead of minutes, or minutes entered where the payer expects units, so the number looks invalid.
  • Start and stop times missing for a payer or jurisdiction that requires them in addition to total time.
  • End time before start time, often when a case crosses midnight.
  • Time reported as zero because charge entry pulled a default.
  • Discontinuous time, such as an anesthesia case with a break, added up incorrectly.

How to fix it

  1. Get the times from the record, such as the anesthesia record’s start and end, and note any interruptions.
  2. Calculate total time following the payer’s rules for how time is counted and whether breaks are excluded.
  3. Report it in the format the payer expects, whether minutes, units, or both, and add start and stop times where required.
  4. Check the times against the date of service for cases that crossed midnight.
  5. Submit a corrected claim with resubmission code 7 and the original claim number.

How to prevent it

Capture start and end times electronically from the clinical record rather than keying them. Set up payer-specific rules in your billing system for whether time is reported as minutes or units. A simple edit that stops claims with zero or negative time will catch many errors.

Codes that may appear with N443

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim lacks information; N443 identifies the time data as missing or invalid.
  • CO-152 (Payer deems the information submitted does not support this length of service.): The information submitted does not support the length of service billed.
  • N203 (Missing/incomplete/invalid anesthesia time/units.): Anesthesia time or units are missing, incomplete, or invalid.
  • M53 (Missing/incomplete/invalid days or units of service.): Days or units of service are missing, incomplete, or invalid.
  • N439 (Missing anesthesia physical status report/indicators.): Anesthesia physical status information is missing.

N443 FAQ

Which services need begin and end times?

Anesthesia is the most common. Some payers also want times for other time-based services, such as critical care, prolonged services, or certain therapies. Requirements vary by payer.

How is anesthesia time reported?

Generally as minutes of anesthesia time in the unit field of the anesthesia line, with the qualifier the payer expects. Some payers or jurisdictions also want the start and stop times.

What if the times on the claim and the record differ?

Use the documented times. If they conflict, correct the claim to match the record and resubmit.